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S' <7 


CATECHISM 

OF  THE  ' 

LOCOMOTIVE. 


SECOND  EDITION, 


BY- 


MATTHIAS  N.  FOR 

Mechanical  Engineer. 


FORTY-SIXTH  THOUSAND. 


PUBLISHED  BY 

THE  RAILROAD  GAZETTE,  73  BROADWAY,,  NEW  YORK, 

1891. 


ENGINEERING  LIBRARY 


TO  THE  FIRST  EDITION. 


Books,  like  individuals,  have  their  histories,  and  it  seems  but  proper 
that,  in  introducing  them,  somewhat  of  their  ancestry  should  be  detailed. 
The  present  book  originated  in  this  wise  : the  publishers  of  the  Railroad 
Gazette  procured  a copy  of  the  “ Katechismus  der  Einrichtung  und  des 
Betriebes  der  Locomotive,”  by  Georg  Kosak.  As  no  English  translation 
of  this  excellent  little  book  was  known  to  be  in  existence,  the  editors  of 
the  above  paper  determined  to  translate  it  and  adapt  it  to  the  American 
practice  in  the  construction  and  management  of  locomotive  steam  engines, 
and  republish  it  in  their  journal.  The  translation  was  therefore  made  and 
submitted  to  the  writer  for  revision  and  adaptation,  according  to  the  orig- 
inal intention.  Before  the  latter  was  entertained,  however,  he  had  com- 
menced writing  an  elementary  treatise  on  the  locomotive.  In  revising  the 
first  part  of  the  translation  of  Mr.  Kosak’s  book,  it  was  found  that  the 
latter  occupied  only  to  a very  limited  extent  the  ground  which  the  writer 
had  “staked  out”  in  his  own  incomplete  plan.  He  therefore  concluded 
to  abandon  the  original  intention  of  “adapting”  Mr.  Kosak’s  work,  and 
determined  to  rewrite  it  and  make  substantially  a new  book  of  it.  For 
the  “ idea,”  however,  and  to  some  extent  its  plan,  and  for  much  valuable 
material,  the  author  must  acknowledge  his  indebtedness  to  Mr.  Kosak. 
In  some  few  cases  the  language  of  the  translator  has  been  employed,  in 
part  or  in  whole,  without  quotation  marks,  but  with  an  acknowledgment 
in  a foot-note.  A similar  plan  has  also  been  pursued  in  using  some  other 


IV 


Preface. 


books.  This  was  done  to  avoid  cutting  up  paragraphs  and  sentences  into 
fragmentary  parts  with  numerous  quotation  marks. 

The  following  books  hayfe  been  consulted  and  used  in  writing  the  Cate- 
chism of  the  Locomotive : Heat  considered  as  a Mode  of  Motion,  by  Prof. 
Tyndall ; The  Conservation  of  Energy,  by  Balfour  Stewart ; Railway  Ma- 
chinery, by  D.  K.  Clark;  Treatise  on  the  Locomotive  Engine,  by  Zerah 
Colburn;  Treatise  on  the  Steam  Engine,  by  W.  J.  M.  Rankine ; Indicator 
Experiments  on  Locomotives,  by  Prof.  Bauschinger;  Richards’  Steam  In- 
dicator, by  Charles  T.  Porter;  Die  Schule  des  Locomotivfuhrers,  by  J. 
Brosius  and  R.  Koch ; Mechanics,  by  A.  Morin ; The  New  Chemistry,  by 
J.  P.  Cooke,  Jr.;  Combustion  of  Coal  and  the  Prevention  of  Smoke,  by  C. 
Wye  Williams;  A Treatise  on  Steam  Boilers,  by  Robert  Wilson;  Reports 
of  the  American  Railway  Master  Mechanics’  Association;  Link  Valve 
Motion,  by  William  S.  Auchincloss,  and  Emergencies  ahd  How  to  Treat 
Them,  by  Dr.  Joseph  W.  Howe. 

For  the  title  of  the  book  an  apology  is  perhaps  needed,  as  the  word 
Catechism  is  associated  in  nearly  all  persons’  minds,  we  will  trust,  with 
early  religious  and  theological  instruction,  and  therefore  a Catechism  of 
the  Locomotive  is  very  apt  to  sound  more  ludicrous  than  scientific.  The 
title  of  Mr.  Kosak’s  book  was  adopted  before  it  was  determined  to  rewrite 
it,  and  it  was  afterwards  deemed  best  not  to  change  it.  To  those  who  are 
disposed  to  smile  at  it,  the  precedent  of  Mr.  Bourne’s  excellent  Catechism 
of  the  Steam  Engine  is  quoted,  and  if  they  will  refer  to  Webster’s  Diction- 
ary for  the  definition  of  the  word  “catechism,”  they  will  find  that  it  means 
“ an  elementary  book  containing  a summary  of  principles  in  any  science 
or  art,  but  appropriately  in  religion,  reduced  to  the  form  of  questions  and 
answers,  and  sometimes  with  notes,  explanations  and  reference  to  authori- 
ties,” which  describes  exactly  what  the  present  book  is  intended  to  be. 

To  persons  accustomed  to  books  and  study,  the  catechetical  form  is 
very  apt  to  seem  cumbrous  and  awkward,  but  it  has  some  very  decided 
advantages  in  writing  for  those  who  have  not  acquired  studious  habits  of 
thought.  To  such  the  question  asked  presents  first  a distinct  image  of 
the  subject  to  be  considered,  so  that  the  explanation  or  instruction  which 


Preface. 


v 


follows  is  much  more  apt  to  be  understood  than  it  would  be  if  no  such 
question  had  been  asked. 

The  author  is  indebted  to  Mr.  D.  B.  Grant  for  the  use  of  drawings  from 
which  most  of  the  engravings  of  details  of  locomotives  with  which  this 
book  is  illustrated  have  been  made,  and  to  other  locomotive  builders, 
whose  engines  are  illustrated  in  the  full-page  plates,  for  the  drawings 
thereof.  He  has  also  received  very  valuable  aid  from  Mr.  Richard  H. 
Buel,  Mechanical  Engineer;  Mr.  William  Buchanan,  Master  Mechanic  of 
the  Hudson  River  Railroad;  Mr.  Frank  D.  Child,  Superintendent  of  the 
Hinkley  Locomotive  Works;  and  Mr.  E.  T.  Jeffrey,  Assistant  Superinten- 
dent of  Machinery  of  the  Illinois  Central  Railroad. 

The  object  in  writing  the  book  was  to  furnish  a clear  and  easily  under- 
stood description  of  the  principles,  construction  and  operation  of  the  loco- 
motive engine  of  the  present  day,  a subject  which  is  not  concisely  or 
adequately  treated  in  any  one  similar  book.  If  the  author  has  succeeded 
in  making  what  he  has  written  plain  to  plain  people,  his  aim  will  be  fully 
accomplished. 

No.  73  Broadway , New  York,  1873. 


PREFACE 


TO  THE  SECOND  EDITION. 


The  first  edition  of  the  Catechism  of  the  Locomotive  was  written  in 
1873.  Since  then  many  changes  and  improvements  have  been  made  in 
the  construction  of  locomotives,  so  that  in  preparing  a second  edition  of 
the  book  the  first  one  had  to  be  thoroughly  revised,  and  to  a great  extent 
rewritten,  and  a great  deal  of  entirely  new  matter  had  to  be  added  to 
bring  it  up  to  the  present  “ state  of  the  art  ” of  locomotive  engineering. 
Most  of  the  illustrations  are  entirely  new,  and  have  been  selected  from  the 
latest  practice  in  this  country.  Additional  chapters  have  been  added  on 
Force  and  Motion;  Resolution  of  Motion  and  Forces;  the  Principles  of 
the  Lever ; the  Action  of  the  Piston,  Connecting-Rod  and  Crank ; Action 
of  the  Pistons,  Cranks  and  Driving-Wheels;  the  Westinghouse  Air- 
Brake;  the  Care  and  Use  of  Air-Brakes;  and  the  Eames  Vacuum  Driving 
Wheel  Brake. 

The  difficulty  has  been  to  keep  the  book  within  the  limits  of  size  to 
which  an  elementary  treatise  should  be  confined.  This  limitation  made 
it  compulsory  to  omit  much  which  ought  to  be  discussed  and  described  in 
any  complete  treatise.  Among  the  omissions  is  a description  of  com- 
pound locomotives  which  are  now  attracting  a great  deal  of  attention  in 
this  country  and  in  Europe.  The  development  of  compound  locomotives 
is,  however,  to  a great  extent — especially  in  this  country — still  in  an  em- 
bryonic state,  and  no  well  established  practice  has  yet  been  developed  in 
their  construction.  Probably  in  a third  edition  of  this  book,  this  type  of 
locomotive  will  demand  distinct  consideration  and  full  description. 


Preface. 


Vll 


I must  here  acknowledge  my  indebtedness  to  Messrs.  Burnham,  Parry, 
Williams  & Co.,  proprietors  of  the  Baldwin  Locomotive  Works,  for 
drawings,  photographs  and  assistance  in  the  work  of  revision ; to  the 
Schenectady  Locomotive  Works  and  other  manufacturers  of  the  loco- 
motives of  which  engravings  are  given  in  the  following  pages;  to  the 
Westinghouse  Air-Brake  Company,  the  Eames  Vacuum-Brake  Company, 
and  to  other  manufacturers  whose  machinery  and  appliances  have  been 
illustrated  and  described.  I am  also  obliged  to  express  anew  my  indebt- 
edness to  Mr.  William  Buchanan,  Superintendent  of  Machinery  of  the 
New  York  Central  & Hudson  River  Railroad  for  much  valuable  assistance. 

The  excellent  little  treatise  on  the  Steam  Engine,  by  George  C.  V. 
Holmes,  and  Arthur  Riggs’  Practical  Treatise  on  the  Steam  Engine,  were 
both  frequently  consulted  and  quoted  from. 

M.  N.  FORNEY. 

No.  145  Broadway , New  York, 

Nov.  9,  1889 . 


CONTENTS 


PAGE 

Preface  to  First  Edition  .......  ii 

Preface  to  Second  Edition  ......  vi 

Introduction  .........  xi 

Chapter  I.  Force  and  Motion  ......  1 

II.  Resolution  of  Motion  and  Forces  . . . .10 

III.  The  Principles  of  the  Lever  ....  19 

IV.  The  Forces  of  Air  and  Steam  . . . .24 

V.  On  Work,  Energy  and  the  Mechanical  Equivalent  of  Heat  34 

VI.  The  Steam  Engine  .....  40 

VII.  The  Expansive  Action  of  Steam  . . . .50 

VIII.  The  Slide-Valve  ......  78 

IX.  The  Action  of  the  Piston,  Connecting-Rod  and  Crank  . 98 

X.  General  Description  of  a Locomotive  Engine  . . 112 

XI.  Different  Kinds  of  Locomotives  ....  121 

XII.  Locomotive  Boilers  .....  168 

XIII.  The  Boiler  Attachments  .....  216 

XIV.  The  Throttle-Valve  and  Steam  Pipes  . . . 254 

XV.  The  Cylinders,  Pistons,  Guide-Bars,  Cross-Heads  and  Con- 
necting-Rods ......  263 

XVI.  The  Valve  Gear  ......  281 

XVII.  Action  of  the  Pistons,  Cranks  and  Driving-Wheels  . 357 

XVIII.  Adhesion  and  Traction  .....  370 

XIX.  Internal  Disturbing  Forces  in  the  Locomotive  . . 376 

XX.  The  Running  Gear  .....  392 

XXL  Miscellaneous  .......  435 

XXII.  Friction  and  Lubrication  .....  440 


X 


Contents. 


PAGE. 


Chapter  XXIII.  Screw-Threads,  Bolts  and  Nuts  . . . 451 

XXIV.  Tenders  . . . . . . 461 

XXV  Water-Tanks  and  Turn-Tables  ....  469 

XXVI.  The  Westinghouse  Air-Brake  . . . 482 

XXVII.  The  Care  and  Use  of  the  Air-Brake  . . . 521 

XXVIII.  The  Eames  Vacuum  Driving-Wheel  Brake  . . 534 

XXIX.  Proportions  of  Locomotives  ....  540 

XXX.  Combustion  ......  551 

XXXI.  The  Resistance  of  Trains  ....  585 

XXXII.  Performance  and  Cost  of  Operating  Locomotives  . 595 

XXXIII.  The  Care  and  Inspection  of  Locomotives  while  in  the 

Engine  House  .....  598 

XXXIV.  Running  Locomotives  .....  617 

XXXV.  Responsibilities  and  Qualifications  of  Locomotive  En- 
gineers . . . . . 637 

XXXVI.  Accidents  to  Locomotives  ....  643; 

XXXVII.  Accidents  and  Injuries  to  Persons  . . . 66$ 


APPENDIX. 


I.  Properties  of  Steam  ......  674 

II.  Hyperbolic  Logarithms  ......  678 


PLATES. 


I.  Stationary  Engine  . . . . .At  end  of  Book. 

II.  Diagram  of  Motion  of  Slide-Valve  . . . “ 

III.  Passenger  Locomotive  .... 

IV.  “ 

V.  “ 

VI.  Westinghouse  Automatic  Air-Brake  . . . 


INTRODUCTION. 


The  Catechism  of  the  Locomotive  is  intended  for  a large  class  of  read- 
ers, among  whom  are  all  kinds  of  railroad  officers  and  employees,  consist- 
ing of  locomotive  engineers,  firemen,  and  the  many  different  kinds  of 
mechanics  employed  in  railroad  shops  and  in  the  construction  of  locomo- 
tive and  other  railroad  machinery  and  material.  Besides  these  there  are 
many  amateur  engineers,  students  and  persons  interested  directly  or  in- 
directly in  railroads,  and  a not  inconsiderable  class  who  are  always  seeking 
information  on  all  subjects  whatsoever.  It  is  evident,  therefore,  that  the 
only  way  to  adapt  the  book  to  all  the  classes  for  whom  it  is  intended,  was 
to  make  it  so  plain  that  the  “wayfaring  man  ” will  have  no  difficulty  in 
comprehending  it.  It  has  therefore  been  written  in  as  simple  and  plain 
language  as  the  writer  could  command,  and  the  subjects  presented  are 
explained  with  the  least  possible  employment  of  either  scientific  or  prac- 
tical technicalities.  The  only  deviation  from  this  plan  will  be  found  in 
the  use  of  algebraic  symbols  to  designate  arithmetical  calculations.  This 
was  done  to  save  space,  and  because  it  was  thought  that  such  symbols 
could  be  explained  so  that  even  those  without  any  knowledge  whatso- 
ever of  algebra  could  easily  comprehend  them.  To  such  as  have  no  such 
knowledge  the  following  explanation  is  given : 

Suppose  it  is  necessary  to  add  two  numbers,  say  1,872  and  468.  The 
calculation,  if  made  arithmetically,  would  be  thus : 

1,872 

468 

2,340 

This  it  will  be  seen  occupies  the  space  of  several  lines  of  print.  If  we 
want  to  express  this  calculation  algebraically,  it  can  be  done  by  simply' 


Introduction. 


xii 

writing  the  two  numbers  and  placing  the  sign  + , called  plus , between  th<\ 
two,  which  indicates  that  they  are  to  be  added  together,  thus: 

1,872  + 468 

To  indicate  what  the  sum  will  be,  or  what  the  two  added  together  will 
amount  to,  the  sign  =,  called  equal  lo,'  or  the  sign  of  equality,  is  placed 
after  the  two  numbers  and  between  them  and  the  sum,  thus : 

1,872  + 468=2,340, 

which  can  be  read  as  follows : 

1,872  added  to  468  is  equal  to  2,340. 

Now  the  only  use  of  the  algebraic  signs  + and  ==  is  that  they  save  time 
in  writing  and  room  in  printing,  and  when  persons  become  accustomed  to 
their  use  they  make  plain  a number  of  operations  at  a single  glance,  as 
will  be  shown  hereafter. 

In  the  same  way  that  the  sign  + means  added  to,  the  sign  — means  less 
or  subtracted  from,  thus : 

1,872  — 468=1,404, 

which  is  the  same  as  though  it  was  printed  as  follows : 

1,872  less  468  is  equal  to  1,404. 

The  sign  x means  multiplied  by,  or  is  the  sign  of  multiplication.  Thus: 
1,872x468=876,096; 

that  is, 

1,872  multiplied  by  468  is  equal  to  876,096. 

The  sign  -s-  means  divided  by,  thus : 

1,872-5-468=4, 

which  means : 

1,872  divided  by  468  is  equal  to  4. 

The  same  thing  is  expressed  by  putting  a line  under  the  dividend  and 
writing  the  divisor  under  the  line,  thus : 

1,872 

468 

These  signs  are  combined  in  various  ways.  Thus,  supposing  we  wanted 


Introduction. 


xiii 

to  add  1,872  to  468  and  then  divide  the  sum  by  117,  it  would  be  necessary,, 
in  order  to  represent  the  arithmetical  calculation,  to  do  it  as  follows: 

1,872 

468 

117)2,340(20 

234 

0 

Algebraically  it  would  be  stated  thus : 

1,872  + 468 

=20. 

117 

If  you  wanted  to  add  124  to  the  quotient  20  above,  the  calculation  would 
be  as  follows : 

1,872 

468 

117)2, 340(  20 
234  124 

0 144 

This  operation  could  be  expressed  by  writing  it  as  follows : 

1,872  + 468 

+ 124=144. 

117 

If  we  wanted  to  multiply  the  quotient  20  by  124  we  would  simply  put 
the  sign  x instead  of  + before  124,  thus : 

1,872x468 

x 124=2,480. 

117 

The  sign  of  subtraction  or  division  can  be  used  in  the  same  way. 

By  carefully  reading  these  explanations  it  is  believed  that  any  one,  with 
nothing  more  than  an  ordinary  knowledge  of  the  four  elementary  rules 
of  arithmetic,  can  understand  all  the  mathematics  contained  in  the  follow- 
ing pages.  A little  explanation  may  also  be  needed  of  the  method  of 
representing  machinery  and  other  structures  by  mechanical  drawings. 


XIV 


Introduction. 


If  we  want  to  represent  any  object,  say  an  apple,  as  it  appears  when 
looking  at  it  from  the  side,  we  make  a drawing  of  it  as  shown  at  fig.  B, 
which  is  called  a side  view. 


Fig.  D.  Vertical  Section. 


Fig.  E.  Sectional  Plan. 


If  we  represent  it  as  it  will  appear  if  we  are  above  it  and  looking  down 
on  it,  as  shown  by  fig.  A , it  is  called  a top  view  or  plan,  and  if  the  object 
is  turned  upside  down  and  is  represented  as  in  fig.  C,  it  is  called  an  in- 
verted plan. 

If  we  want  to  show  the  inside  of  the  apple,  say  the  seeds  and  core,  we 
can  cut  it  in  half  vertically  and  represent  it  as  shown  at  fig.  D,  which  is 
then  called  a section  or  sectional  view  of  the  apple.  It  is  evident,  too,  that 
it  might  be  desirable  to  show  the  arrangement  of  the  seeds  in  the  apple 


Introduction. 


XV 


as  they  would  appear  if  it  was  cut  through  in  the  other  direction,  say  on 
the  line  c d,  fig.  B,  and  as  is  shown  by  fig.  E.  There  are  therefore  two 
kinds  of  sections ; one  fig.  D,  in  which  the  object  is  supposed  to  be  cut 
through  vertically,  and  therefore  called  a vertical  section,  the  other  when 
the  object  is  supposed  to  be  cut  through  horizontally,  and  therefore  called 
a horizontal  section,  or  sectional plan,  as  shown  by  fig.  E.  In  order  to  dis- 
tinguish the  parts  which  are  represented  as  though  they  were  cut  in  two, 
from  those  whose  surfaces  only  are  shown,  it  is  customary  to  shade  sec- 
tional views  with  parallel  lines,  as  shown  in  figs.  D and  E.  Sections  are 
also  sometimes  represented  with  solid  black  surfaces,  as  in  Plate  IV,  and 
in  the  engraving  of  an  injector,  fig.  181. 

It  is  often  desirable  in  drawings  to  show  some  internal  parts  on  an  ex- 
terior view  of  a machine  or  other  structure.  In  such  cases  the  interior 
parts  are  represented  by  dotted  lines.  Thus,  to  show  the  position  and 
form  of  the  seeds  of  the  apple  in  figs.  B and  C,  they  are  represented  by 
dotted  lines. 

The  appearance  of  any  object,  whether  it  be  an  apple  or  a locomotive, 
of  course  depends  upon  our  position  in  relation  to  it.  Thus,  fig.  B is  a 
side  view  of  an  apple,  and  Plate  Ilia  side  view  of  a locomotive  ;*  fig.  D 
is  a vertical  section  of  an  apple,  and  Plate  IV  a section  of  a locomotive. 
Fig.  A and  Plate  Vf  are  plans  of  these  same  objects. 

It  is  obvious  that  a number  of  different  sectional  views  can  be  made  of 
any  object,  especially  of  a machine.  Thus,  we  could  suppose  a locomotive 
cut  through  vertically  and  lengthwise,  as  is  shown  in  Plate  IV.  It  is  of 
course  possible  to  represent  a transverse  section  of  a machine  like  a loco- 
motive at  a great  many  different  points ; for  example,  it  could  be  shown 
as  though  it  was  cut  through  the  smoke-stack,  as  in  fig.  98,  or  a section  of 
the  boiler  farther  back,  as  it  is  shown  in  fig.  122.  Usually  when  a section 
is  shown  through  a cylindrical  object  like  a chimney  or  boiler,  it  is 
shown  through  its  centre.  If,  however,  this  is  not  apparent  from  the 
drawing  or  engraving,  it  should  be  stated  at  what  point  it  is  supposed  to 
be  taken,  thus  the  cross-section,  fig.  122,  of  the  boiler  is  through  the  fire- 
box. 

It  is  also  customary,  in  drawings  of  machinery,  to  take  great  liberties 
with  the  objects  represented  and  to  show  them  with  parts  removed  or 
broken  away,  if  their  construction  can  thus  be  made  plainer.  It  should 
be  remembered  that  the  purpose  of  drawings  of  this  kind  is  not  to  give  a 


* The  cylinder,  i,  is  shown  in  section  in  this  engraving, 
t Part  of  the  boiler  is  supposed  to  be  removed  in  this  view. 


XVI 


Introduction. 


pictorial  representation  of  the  object  as  it  appears  to  the  eye,  but  to  make 
its  construction  and  mode  of  operation  apparent  to  the  mind.  In  such 
drawings,  therefore,  all  perspective  is  disregarded.  It  would  lead  us  too 
far  were  we  to  explain  the  reasons  for  this,  and  therefore  readers  must 
accept  the  assertion  without  the  proof. 

In  reading  the  following  pages  for  the  first  time,  many  persons,  especi- 
ally those  who  have  had  somewhat  limited  educational  advantages  or 
technical  training,  will  perhaps  find  it  best  to  omit  chapters  IX,  XVI  and 
XVII,  which  they  may  find  are  rather  hard  reading.  These  chapters  can 
probably  be  taken  up,  by  such  persons,  to  better  advantage  after  the  others, 
have  been  read. 


CATECHISM  OF  THE  LOCOMOTIVE 

(REVISED  AND  ENLARGED). 


By  M.  N.  Forney. 


CHAPTER  I. 


FORCE  AND  MOTION. 


Question  1.  How  do  we  get  our  first  notion  of  the  nature  or  of  the 
effect  of  force  ? 

Answer.  It  is  suggested  to  us  by  the  so-called  muscular  sense  ; that  is, 
we  have  a peculiar  feeling  of  pressure  when  we  try  to  move  any  object  or 
piece  of  matter. 

Question2.  What  is  “force?” 

Answer.  We  know  nothing  about  the  absolute  nature  of  force.  All 
that  we  know  is  what  we  can  learn  through  the  senses  of  its  effects.  It 
has  been  defined  as  “ that  which  affects  the  motion  of  matter ; ” and  again 
as  “ any  action  between  two  bodies  which  changes,  or  tends  to  change, 
their  relative  condition  as  to  rest  or  motion.”  In  the  plainer  words  of  a 
distinguished  author*  “ the  word  force  is  obviously  to  be  applied  to  any 
pull,  push,  pressure,  tension,  attraction  or  repulsion,  etc.,  whether  applied 
by  a stick  or  a string,  a chain  or  a girder,  or  by  means  of  an  invisible  me- 
dium such  as  the  attraction  of  gravitation  or  electricity.” 

Question  3.  How  is  the  motion  of  one  body  in  relation  to  others  fro-  f 


duced?  | 

Answer.  It  is  produced  by  the  exertion  on  it  of  force. 

QUESTION  4.  Are  bodies  ever  made  to  move  in  any  other  way  excepting 
by  the  action  of  some  force  or  forces  on  them  ? 

Answer.  No.  Part  of  what  is  called  the  first  law  of  motion  is  that  “ a 
body  at  rest  remains  at  rest  until  some  force  acts  upon  it  to  set  it  in  motion  ” 


*P.  G.  Tait.  “ Recent  Advances  in  Physical  Science,”  p.  35. 


Catechism  of  the  Locomotive. 


Question  5.  V/hat  is,  the  other  portion  of  the  first  law  of  motion  ? 

Aystyep.  u That  a body  in  motion  continues  with  its  motion  unchanged . 
either  in  dhr&rficji  or  velocity , until  acted  upon  by  some  external  force." 
Thus,  a top  can  be  made  to  spin  in  the  open  air  for  a minute  or  more,  but 
in  a vacuum  it  will  spin  a much  longer  time,  because  there  it  has  not  the 
resistance  of  the  atmosphere  to  overcome.  If  it  be  accurately  balanced 
and  revolves  on  a small  steel  point  which  bears  on  a glass  plate,  it  can  be 
made  to  spin  in  a vacuum  for  an  hour  or  longer,  because  there  the  resis- 
tance, or  force,  which  is  opposed  to  its  revolution  is  reduced  to  the  lowest 
possible  amount.  Neverthejcs^this  however  small,  will  check  the 

speed  of  the  revolutions  of IjP? top,  aim  finally  it  will  cease  to  spin  alto- 
gether. As  there  is  always  some  force  which  resists  motion,  there  is  a 
corresponding  tendency  which  causes  bodies  about  us,  as  we  know  them, 
to  come  to  a state  of  rest. 

Question  6.  What  is  meant  by  “ inertia  ? ” 

Answer.  Inertia  has  been  defined  as  “ that  property  of  matter  by  which 
it  tends  when  at  rest  to  remain  so,  and  when  in  motion  to  continue  in  mo- 
tion.” Thus,  if  a cannon-ball  be  suspended  from  a long  string  so  that  it 
can  swing  freely  a force  must  be  exerted  against  it  to  move  it,  or  if  it  is 
moving  a force  must  be  exerted  to  resist  its  movement  to  stop  it. 

Question  7.  When  is  motion  said  to  be  uniform? 

Answer.  When  a body  passes  over  equal  spaces  in  equal  periods  of 
time.  Thus,  the  motion  of  the  minute  hand  of  a clock  is  uniform,  be- 
cause it  passes  over  equal  spaces  on  the  clock  face  in  each  minute  or  hour. 
A railroad  train  is  said  to  have  a uniform  velocity  when  it  runs  successive 
miles  in  the  same  number  of  minutes  or  seconds. 

Question  8.  What  is  meant  by  accelerated  and  retarded  motion  ? 

Answer.  Motion  is  accelerated  when  the  spaces  passed  over  in  equal 
periods  of  time  become  greater  and  greater,  and  motion  is  retarded  when 
these  spaces  become  smaller  and  smaller.  Thus,  if  a railroad  train  should 
run  one  mile  in  five  minutes,  the  next  one  in  four,  and  the  following  ones  in 
three  and  two  minutes  each,  its  motion  would  be  said  to  be  accelerated. 
A stone  falling  from  any  height  is  another  example  of  accelerated  motion. 
On  the  other  hand,  a railroad  train,  when  it  is  being  stopped,  and  a stone 
thrown  upward\£fe  examples  of  retarded  motion. 

Question  0:  tilVhat  is  meant  by  unifonnly  accelerated  or  uniformly  re- 
tarded motion  ? 

Answer.  Motion  is  said  to  be  uniformly  accelerated  or  retarded  when 
the  increase  or  diminution  of  velocity  in  each  interval  of  time  is  the  same. 


Force  and  Motion. 


3 


Thus,  if  a railroad  train  should  have  a velocity  of  two-tenths  of  a mile  at 
the  end  of  the  first  minute,  three-tenths  at  the  end  of  the  second,  four- 
tenths  at  the  end  of  the  third,  and  five-tenths  at  the  end  of  the  fourth,  its 
motion  would  be  said  to  be  uniformly  accelerated.  A falling  body  is  an- 
other example.  Its  velocity  is  32.2  feet  per  second  at  the  end  of  the  first 
second,  64.4  at  the  end  of  the  second,  96.6  at  the  end  of  the  third,  etc.  In 
the  case  of  the  railroad  train,  the  velocity  is  increased  one-tenth  of  a mile 
for  each  minute,  and  that  of  the  falling  body  is  increased  32.2  feet  for  each 
second. 

Question  10.  How  is  the  velocity  of  a moving  body  increased  or  dimin- 
ished? 

Answer.  By  the  action  of  force  on  it.  If  this  force  is  exerted  in  the 
direction  of  the  movement  of  the  body,  its  velocity  will  be  increased  so 
long  as  the  force,  or  the  motive  power  as  many  call  it,  is  greater  than  the 
resistance  opposed  to  it.  Whenever  the  motive  power  equals  the  resist- 
ance, then  the  moving  body  will  have  a uniform  speed  ; and  when  the  re- 
sistance becomes  greater  than  the  moving  form,  the  velocity  will  be  re- 
tarded. 

Question  11.  How  is  this  illustrated  in  a railroad  train  and  a loco- 
motive ? 

Answer.  When  the  locomotive  starts,  the  speed  of  the  train  is  increased, 
until  its  resistance  is  equal  to  the  force  or  power  exerted  by  the  engine. 
If  the  train  reaches  an  up  grade,  and  its  resistance  is  consequently  increased, 
its  speed  will  be  retarded.  On  a level,  the  speed  will  also  be  retarded  if 
steam  is  shut  off,  either  partially  or  wholly,  so  as  to  diminish  the  force  or 
power  which  the  engine  exerts. 

Question  12.  What  relation  is  there  between  the  force  exerted  on  a 
moving  object  and  its  velocity  ? 

Answer.  With  any  object  of  a given  weight,  the  greater  the  force  ex^. 
erted  the  quicker  will  the  speed  be  increased  or  diminished.  Every  boy 
has  learned  this  in  drawing  a wagon  or  sled  or  in  trying  to  stop  one  in 
motion. 

Question  13.  Can  we  know  how  much  the  velocity  of  a moving  body 
will  be  increased  or  diminished  by  a known  force,  if  there  is  no  other  resist- 
ance to  motion  excepting  the  inertia  of  the  moving  bodyj^ 

Answer.  Yes,  this  has  been  ascertained  by  the  effect"  of  the  attraction 
of  gravitation,  which  causes  all  objects  to  fall  toward  the  centre  of  the 
earth  if  their  movement  is  not  resisted  by  some  greater  force. 

Question  14.  What  is  the  rate  of  acceleration  of  falling  bodies? 


4 


Catechism  of  the  Locomotive. 


Answer.  It  has  been  found  by  the  most  exact  experiments,  that  at  the 
surface  of  the  earth  all  bodies  falling  in  a vacuum,  where  the  air  offers  no 
resistance,  acquire  a velocity  of  32.2  feet  per  second  at  the  end  of  the  first 
second,  64.4  feet  at  the  end  of  the  second  second  and  96.6  feet  at  the  end 
of  the  third,  and  so  on  with  an  increase  of  32.2  feet  for  each  successive 
second. 

Question  15.  Can  this  increase  in  motion  be  represented  in  any  way  by 
drawing  ? 

Answer.  Yes,  we  can  draw  a diagram  which  will  show  to  the  eye  the 
rate  at  which  a body  falls.  To  do  this  let  us  suppose  that  a stone  is 
allowed  to  fall  from  0,  fig.  1,  and  that  the  distance  0 1 is  drawn  to  any  con- 
venient scale  to  represent  the  distance,  16.1  feet,  that  it  will  fall  in  the  first 
second ; 1 2 the  distance,  48.3  feet,  that  it  will  fall  the  second  second ; and 
2 3,  3 4,  4 5 and  5 6 the  distances  it  will  fall  in  successive  seconds.  If  now 


1"  2"  3"  4"  R" 

Fig.  2.  Diagram  of  Falling  Body. 


Fig.  1.  Diagram  of  Falling  Body. 


from  1 a horizontal  line,  1 1',  be  drawn  whose  length  represents  32.2  feet, 
the  velocity  the  stone  will  acquire  at  the  end  of  the  first  second,  and  2 2', 
3 3',  etc.,  be  drawn,  each  representing  the  velocity  in  feet  per  second  that 
the  stone  has  acquired  at  the  end  of  the  successive  seconds,  and  a curve, 
0 V 2'  3'  4'  5'  6',  be  drawn  through  the  extremities  of  the  horizontal  lines, 
then  the  horizontal  distance  of  the  curve  from  any  point  in  the  vertical 
line  o 6 will  represent  the  velocity  of  the  stone  at  that  point. 

QUESTION  16.  In  what  way  may  this  diagram  be  modified? 

Answer . For  some  purposes,  which  will  be  explained  in  a future  chap- 


Force  and  Motion. 


5 


ter,  it  is  more  convenient,  as  in  fig.  2,  to  make  the  spaces  0 1,  1 2,  2 3,  etc., 
between  the  horizontal  lines,  which  represents  seconds,  equal  to  each  other. 
The  lines  1 1',  2 2',  etc.,  can  then  be  drawn  as  in  the  preceding  diagram, 
to  represent  the  velocity  of  the  stone  at  the  end  of  each  second,  and  the 
line  0 1'  2'  3',  passing  through  their  extremities,  will  then  be  a straight 
line  if  the  fall  of  the  stone  is  uniformly  accelerated,  as  it  would  be  if  it  fell 
in  a vacuum. 

Question  17.  How  is  the  law  which  governs  the  velocity  of  falling 
bodies  still further  illustrated  by  the  diagram  ? 

Answer.  Before  this  question  is  answered  it  will  again  be  explained, 
and  should  be  clearly  understood  by  the  reader,  that  in  fig.  1 the  spaces 
between  the  horizontal  lines  represent  the  distances  through  which  the 
stone  falls  in  successive  seconds,  whereas,  in  fig.  2 the  spaces  between  the 
horizontal  lines  represent  the  periods  of  time  or  seconds  occupied  by  the  fall. 

In  both  figures,  the  lines  1 V represent  the  velocity,  32.2  feet  per  sec- 
ond, that  the  stone  has  acquired  at  the  end  of  the  first  second.  If  its  fall 
was  not  still  further  accelerated  then  the  horizontal  distance  of  the  dotted 
line,  V 1"  from  0 6 would  represent  its  velocity.  But  in  falling  from  1 to 
2 it  again  acquires  an  addition  of  32.2  feet  per  second — represented  by 
the  line  a 2' — to  its  velocity,  so  that  at  the  end  of  the  second  second  it 
is  t>4.4  feet.  By  examining  the  diagram,  it  will  be  seen  that  during  each 
second  of  the  fall  the  velocity  previously  acquired  by  the  stone  is  increased 
by  the  amounts  represented  by  the  lines  b f , c f,  d f and  e 6 ',  each  equal 
to  32.2  feet. 

Question  18.  How  is  the  law  which  governs  the  distance  through 
which  a body  will fall  illustrated  by  the  diagra7n  ? 

Answer.  As  shown  in  fig.  2 the  stone  starts  from  a state  of  rest  at  o, 
and  at  the  end  of  the  first  second  has  acquired  a velocity  of  32.2  feet  per 
second.  Its  average  velocity  during  the  first  second  is,  therefore,  one-half 
of  32.2  feet,  so  that  it  falls  16.1  feet  in  that  time.  As  it  has  acquired  a 
velocity  of  32.2  feet  at  the  end  of  the  first  second,  it  would  fall  that  dis- 
tance during  the  second  second,  but  during  that  time  it  acquires  an  addi- 
tional velocity  of  32.2  feet  which  will  cause  its  fall  16.1  further  than  it 
would  if  it  was  not  accelerated  during  that  period.  The  distance  that  it 

will  fall  in  the  second  second  is,  therefore,  32.2  + ??^ =48.3  feet.  From 

2 

the  diagrams  it  will  be  seen  that  in  each  successive  second  the  distance 
that  the  stone  falls  is  16.1  feet  more  than  that  through  which  it  fell  the 
preceding  second. 


6 


Catechism  of  the  Locomotive. 


QUESTION  19.  How  can  the  velocity  of  a falling  body  be  calculated ?* 

Answer.  As  shown  by  the  diagrams  the  velocity  which  a stone  acquires 
is  equal  to  32.2  feet  per  second  at  the  end  of  the  first  second ; at  the  end 
of  the  second  second  it  is  twice  32.2 ; at  the  end  of  the  third  second  it  is 
three  times,  and  so  on ; so’ that  if  we  multiply  32.2  by  the  number  of  seconds 
that  the  body  has  fallen  will  give  its  velocity. 

Question  20.  How  is  the  distance  through  which  a body  will  fall  in  a 
given  time  calculated? 

Answer.  Multiply  the  square  of  the  number  of  seconds,  that 
the  body  has  fallen,  by  16.1.  The  product  will  be  the  distance 

FALLEN. 

Question  21.  Do  all  bodies  fall  at  the  same  velocity  ? 

Answer.  In  a vacuum,  where  the  atmosphere  offers  no  resistance,  they 
all  fall  at  the  same  velocity.  A feather  will  fall  as  fast  as  a piece  of  lead, 
and  a cannon-ball,  weighing  one  pound,  will  fall  as  quickly  as  one  weigh- 
ing a hundred. 

Question  22.  What  relation  is  there  between  the  weight  and  the  motion 
of  a body  ? 

Answer.  The  heavier  a body  is,  the  greater  will  be  the  force  required 
to  move  it  and  to  accelerate  or  retard  its  motion.  This  we  all  learn  by 
ordinary  experience,  as  in  drawing  a wagon  or  moving  a piece  of  furniture. 
We  are  apt  to  attribute  it  to  the  fact  that  the  friction  of  heavy  objects 
when  rolling  or  sliding  is  greater  than  light  ones,  which  is  part  of  the  rea- 
son why  more  force  is  required  to  move  them ; but  if  we  suspend  two 
cannon-balls,  one  weighing  one  pound  and  the  other  a hundred  pounds, 
by  long  cords,  so  that  they  can  swing  freely  like  a pendulum,  with  little  or 
no  friction,  we  will  find  that  it  takes  a much  greater  force  to  move  the 
heavy  ball  than  is  needed  to  move  the  light  one  the  same  distance  in  the 
same  time.  In  this  case  there  is  hardly  any  resistance  excepting  inertia , 
which  opposes  the  swinging  of  the  balls. 

Question  23.  What  relation  is  there  between  the  weight  and  the  in- 
ertia of  a body  ? 

Answer.  They  are  proportional  to  each  other.  That  is,  a body  weigh- 
ing a hundred  pounds  has  twice  as  much  inertia  as  one  weighing  fifty.  It 
will  be  found  that  the  heavy  suspended  cannon-ball  will  take  a hundred 
times  as  much  force  to  cause  it  to  swing  a given  distance  in  a given  time 
as  is  needed  for  the  light  one.  It  is  assumed  that  they  are  suspended  by 

* This  rule  is  correct  only  for  bodies  falling  in  a vacuum,  but  is  approximately  correct  for 
heavy  bodies  falling  in  the  atmosphere. 


Force  and  Motion. 


7 


very  long  cords  so  that  the  arc  or  path  in  which  they  swing  does  not  differ 
appreciably  from  a straight  line. 

Question  24.  If  this  is  the  case  why  is  it  that  a heavy  object  will  fall 
as  quickly  as  a light  one  ? 

Answer.  It  is  because  its  weight,  which  is  the  force  that  causes  the 
heavy  body  to  fall,  is  proportional  to  its  inertia.  That  is,  each  pound  of 
inertia — if  we  may  so  express  it — has  one  pound  of  weight  or  force  to  im- 
pel the  body  downward. 

Question  25.  Would  a force  acting  upward,  horizontally  or  in  any 
other  direction  have  the  same  effect  f 

Answer.  Yes,  if  it  acted  against  the  body  which  could  move  freely  and 
without  any  other  resistance  excepting  that  of  its  own  inertia. 

Question  26.  How  can  this  be  more  clearly  illustrated  and  explained? 

Answer.  To  make  this  clear,  we  will  again  suppose  that  we  have  a can- 
non-ball, B,  fig.  3,  suspended  by  a very  long  string,  A,  so  that  it  can 
move  freely,  and  that  the  arc  in  which  it  will  swing  will  not  differ  ap- 
preciably from  a straight  line.  We  will  also  suppose  that  we  have  a long 


Fig.  3.  Suspended  Cannon-Ball. 

cylinder,  C,  with  a piston,  P,  and  rod,  R,  fitted  in  it  so  that  they  can 
move  freely  in  the  cylinder — the  rod,  R,  being  attached  to,  or  bearing 


8 


Catechism  of  the  Locomotive. 


against  the  cannon-ball,  B.  If,  now,  we  were  to  admit  steam  or  com- 
pressed air  into  the  cylinder  by  the  pipe  S,  of  such  a pressure  that  the 
force  exerted  on  the  cannon-ball  is  equal  to  its  weight,  then,  assuming 
that  there  is  no  friction  of  the  piston,  the  ball  would  be  moved  in  the  di- 
rection in  which  the  force  or  pressure  on  it  is  exerted,  and  in  a given  time 
it  would  acquire  the  same  velocity  that  it  would  if  it  were  allowed  to  fall 
freely.  In  the  one  case,  the  pressure  in  the  piston  acting  in  a horizontal 
direction  is  the  accelerating  force,  and  in  the  other,  the  accelerating  force 


•*  Fig.  4.  Cannon  Ball  Moving  Vertically. 

is  the  attraction  of  gravitation  or  weight  of  the  cannon-ball  which  acts 
downward.  If  these  forces  are  equal  to  each  other  the  velocity  and  accel- 
eration of  the  suspended  ball  in  a horizontal  direction  will  be  the  same  as 
if  it  was  allowed  to  fall  vertically  an  equal  distance. 

If  we  had  a vertical  cylinder,  C,  as  shown  in  fig.  4,  with  a ball,  B,  piston,  P, 
and  rod,  R,  then  if  the  pressure  on  the  piston  was  equal  to  its  own  weight 
and  that  of  the  rod  and  ball,  the  two  forces,  that  is,  the  pressure  under  the 
piston  acting  upward  and  the  attraction  of  gravitation  acting  downward, 
would  just  balance  each  other,  and  there  would  be  no  motion.  If,  how- 
ever, the  pressure  against  the  piston  was  double  that  of  the  weight  on  it, 


Force  and  Motion. 


9 


then  there  would  be  an  upward  force  equal  to  twice  the  weight  of  the 
parts,  which  would  be  resisted  by  their  inertia  alone.  What  might  be 
called  the  net  upward  force,  or  that  which  would  be  exerted  to  push  the 
parts  upward,  after  the  attraction  of  gravitation  had  been  overcome,  would 
then  be  equal  to  the  weight  of  the  parts.  Consequently,  under  these  con- 
ditions the  cannon-ball  would  fall  upward — if  such  an  expression  may  be 
used — at  the  same  velocity  that  it  would  fall  downward  by  its  own  weight. 

Question  27.  If  the  force  acting  on  a moving  body  is  increased  or  di- 
minished what  effect  does  it  have  on  the  velocity  ? 

Answer.  The  velocity  is  in  exact  proportion  to  the  force  acting  on  it. 
If  you  double  the  force,  you  double  the  velocity.  Thus,  if  the  cylinder 
shown  in  fig.  4 was  turned  upside  down,  and  a pressure  was  then  produced 
on  top  of  the  piston  equal  to  the  weight  attached  to  it,  then  there  would 
be  two  forces  acting  downward  on  the  cannon-ball — its  own  weight  and 
that  due  to  the  pressure  on  the  piston.  If  the  two  are  equal  then  the  can- 
non-ball would  fall  at  double  the  velocity  that  it  would  if  acted  upon  by 
gravitation  alone.  This  principle  is  applied  to  steam-hammers,  which  are 
so  arranged  that  when  a light  blow  is  required  the  hammer-head  is  allowed 
to  fall  by  its  own  weight  alone,  but  when  a harder  blow  is  needed  steam 
is  admitted  above  the  piston  to  force  it  and  the  hammer-head  down 
faster  than  it  would  fall  by  its  own  weight. 


CHAPTER  II. 


RESOLUTION  OF  MOTION  AND  FORCES. 

Question  28.  When  one  object  is  moved  by  two  forces  acting  simultane- 
ously in  different  directions  but  not  opposite  to  each  other,  what  occurs  f 
Answer.  It  moves  in  the  shortest  path  between  the  point  from  which 
it  starts  to  that  which  it  would  reach  in  a given  time  if  acted  upon  by 
each  of  the  forces  separately. 


Fig.  5.  Elevator  and  Billiard-Ball. 

Question  29.  How  can  this  be  shown  ? 

Answer . This  will  be  made  apparent  if  it  be  supposed  that  a billiard- 


Resolution  of  Motion  and  Forces. 


11 


ball  or  other  object  is  rolled  on  the  floor  of  an  elevator — used  for  raising 
and  lowering  goods  or  passengers — while  the  elevator  is  ascending  or  de- 
scending. Thus,  let  A , fig.  5,  represent  a vertical  section  of  the  elevator, 
and  b a billiard-ball.  If  the  distance  from  b to  c is  equal  to  4 feet,  and 
that  from  c to  c'  equal  to  6 feet,  then  if  the  ball  is  rolled  from  b to  c at  the 
rate  of  4 feet  per  second  while  the  elevator  is  standing  still,  the  horizontal 
dotted  line  b c would  represent  its  path.  But  if  the  ball  is  not  rolled, 
and  the  elevator  ascends  at  the  rate  of  6 feet  per  second,  then  the  vertical 
dotted  line  b b'  would  represent  its  path.  If,  however,  the  elevator  is  go- 
ing up  at  the  same  time  that  the  ball  is  rolling,  then,  while  the  latter  is 
moving  horizontally  4 feet,  from  b to  c,  it  is  also  ascending  6 feet,  so  that 
its  path  would  be  represented  by  the  diagonal  line  b c' . 

The  same  principle  is  also  illustrated  if  a boat  is  rowed  across  a river 
which  flows  at  a rate  of,  say,  3 miles  an  hour.  If  the  river  is  a mile 


Fig.  6.  Diagram  of  Movement  of  Boat. 


wide,  and  the  boat  is  rowed  at  a speed  of  4 miles  an  hour,  it  will  take  a 
quarter  of  an  hour  to  cross.  But  while  the  boat  is  being  rowed  across  it 
also  drifts  three-quarters  of  a mile  down  stream  with  the  current,  as  illus- 
trated in  fig.  6,  in  which  R is  the  river  and  A the  starting  point  of  the  boat. 
If  there  was  no  current  in  the  river  and  the  boat  was  rowed  in  the  direc- 
tion A B at  the  speed  mentioned,  it  would  cross  and  reach  B in  a quar- 
ter of  an  hour.  On  the  other  hand,  if  it  were  allowed  to  drift  with  the 
current  and  were  not  rowed,  it  would  float  down  stream  three-quarters  of 
a mile  to  C in  the  same  time.  If,  when  the  boat  reached  C there  was  then 
no  current,  and  the  boat  was  rowed  across,  it  would  reach  D in  15  min- 
utes after  leaving  C.  If,  however,  the  boat  starts  from  A and  is  rowed  in 
the  direction  A B while  it  is  crossing,  it  will  simultaneously  drift  down 
stream  with  the  current,  so  that  it  will  take  the  diagonal  path  A D,  and 


12 


Catechism  of  the  Locomotive. 


will  reach  D in  the  same  time  that  would  be  required  to  row  from  A to  B 
or  C to  *D  if  there  was  no  current,  or  to  float  from  A to  C if  the  boat  was 
not  rowed. 

Question  30.  How  can  we  determine  graphically  the  direction  and 
distance  which  an  object  like  a boat  will  move  if  acted  upon  by  two  forces  as 
described? 

Answer.  If  we  will  draw  one  line  A B , fig.  6,  whose  direction  and 
length  represents  to  any  convenient  scale  the  direction  and  the  distance 
that  the  body  would  be  moved  by  one  force  in  a given  time,  then  draw 
another  line,  B D,  representing  in  the  same  way  the  direction  and  distance 
that  the  object  would  be  moved  by  the  other  force,  and  then  draw  a diago- 
nal line  from  the  starting  point  A to  the  terminal  point  D.  Or  we  may 
proceed  in  the  reverse  order  and  draw  A C first,  and  then  make  C D 
equal  and  parallel  to  A B,  and  then  complete  the  diagram  with  the  diago- 
nal line  A D.  It  should  be  noticed  that  A B must  be  equal  and  parallel 
to  C D,  and  A C equal  and  parallel  to  B D , so  that  the  line  A D is  a diago- 
nal of  a parallelogram  whose  sides  are  equal  and  parallel  to  the  direction 
of  the  two  forces  which  simultaneously  act  upon  the  body. 

In  fig.  5 the  lines  b b'  and  c c'  are  equal  and  parallel,  and  so  are  b c and 
br  c',  so  that  be'  is  a diagonal  of  the  parallelogram  b b'  c'  c.  Hence,  we  see 
that  the  motion  which  results  from  the  action  of  two  forces,  is  the 
diagonal  of  a parallelogram,  the  sides  of  which  represent  the  extent  and 
direction  of  the  motion  which  would  have  been  produced  by  each  force 
acting  separately. 

Question  31.  How  is  the  general  principle  stated  in  scientific  lan- 
guage ? 

Answer.  It  is  said  by  Rankine  : “ If  two  forces  whose  lines  of  action 
traverse  one  point  be  represented  in  direction  and  magnitude  by  the  sides 
of  a parallelogram,  their  resultant  is  represented  by  the  diagonal.” 

Question  32.  How  can  this  be  still further  illustrated? 

Answer.  Let  it  be  supposed  that  a sail-boat  A,  fig.  7,  is  acted  upon  by 
the  wind  so  that  in  a given  time,  say  a half  hour,  it  would  be  moved  in  the 
direction  and  a distance  represented  by  the  line  A B,  and  that  in  the  same 
‘ time  the  tide  would  carry  it  from  A to  C.  Now,  lay  down  A B represent- 
ing, to  any  convenient  scale,  the  effect  of  the  wind,  and  A C that  of  the 
tide,  and  draw  B D equal  and  parallel  to  A C,  and  D C equal  and  parallel 
to  B A , then  the  diagonal  A D will  represent  the  direction  and  the  dis- 
tance the  boat  will  move  under  the  combined  effect  of  wind  and  tide. 

Question  33.  What  is  the  movement  which  results  from  the  combined 


Resolution  of  Motion  and  Forces. 


13 


action  of  two  or  more  forces,  and  which  in  figs.  6 and  y is  represented  by  the 
diagonals  of  the  parallelograms,  named? 

Answer.  It  is  named  the  “ resultant." 


Fig.  7.  Diagram  of  Movement  of  Boat. 


QUESTION  34.  What  are  the  forces  represented  by  the  sides  of  the  par- 
allelogram, and  which  act  upon  a body  to  produce  the  resultant,  called  ? 

Answer.  They  are  called  the  “ components." 

Question  35.  If  we  have  a resultant  and  wish  to  ascertain  two  com- 
ponents acting  in  given  directions  which  would  produce  the  resultant,  how 
can  we  do  it  ? 

Answer.  This  can  be  done  by  drawing  a line  representing  the  resultant 
in  direction  and  length ; then  from  its  extremities  lines  must  be  drawn 
representing  the  direction  of  the  components.  A parallelogram  can  thus 
be  constructed  of  which  the  resultant  is  the  diagonal,  and  the  sides  will 
represent  the  components.  Thus,  suppose  A B,  fig.  8,  represents  the  di- 
rection and  the  distance  which  a boat  is  carried  by  the  combined  action  of 
the  wind  blowing  in  the  direction  A E,  and  of  the  tide  flowing  from  A 
toward  F;  if  we  want  to  find  out  how  far  the  wind  or  how  far  the  tide 
would  carry  the  boat  in  the  time  that  it  moves  from  A to  B,  we  draw  the 
line  A E through  A in  the  direction  of  the  wind,  and  A F also  through  A 
in  the  direction  of  the  tide.  We  then  complete  the  parallelogram  by 
drawing  B E through  B and  parallel  to  A F,  and  F B parallel  to  A E. 
Then  the  side  A E represents  the  distance  the  tide  would  carry  the  boat, 
and  A F that  which  the  wind  would  move  it  while  it  is  going  from  A to  B 
under  their  combined  influence. 


14 


Catechism  of  the  Locomotive. 


Question  36.  What  is  the  process  by  which  two  motions  are  resolved 
into  one,  or  one  into  two,,  which  has  been  described,  called? 

Answer.  It  is  called  the  “ composition  of  motion .” 


F 

Fig.  8.  Parallelogram  of  Motion  and  Forces. 


QUESTION  37.  Can  the  effect  of  two  forces  or  strains  acting  simulta- 
neously on  a body  be  represe?ited  in  the  same  way  ? 

Answer.  Yes. 

QUESTION  38.  How  is  a force  or  strain  represented  by  a line? 

a 


Q 

Fig.  9.  Weight  or  Force  Represented  by  a Line. 

Answer . Forces  are  compared  to  or  measured  by  the  downward  pres- 


Resolution  of  Motion  and  Forces. 


15 


sure  which  a 1-lb.  weight  exerts  at  the  surface  of  the  earth,  so  that  it  is 
easy  to  conceive  that  the  magnitude  of  a pushing  or  pulling  force  may  be 
described  as  equivalent  to  so  many  pounds.  We  may  therefore  take  any 
length  of  line  to  represent  one  pound ; that  is,  a line  one  inch  long  may 
represent  a pound,  one  2 inches  would  represent  2 lbs.,  and  one  6 inches  long 
6 lbs.,  etc.  Or  we  may  take  one-eighth  of  an  inch  to  represent  a pound,  as 
in  fig.  9,  in  which  the  weight  W is  supposed  to  be  equal  to  9 lbs.,  and  the 
line  a b is  made  equal  to  nine-eighths,  or  1£  inches,  and  it  thus  represents  the 
magnitude  of  the  force  or  weight  W.  In  the  same  way,  if  a horse  was 
pulling  on  a rope  and  exerted  a strain  of  100  lbs.,  we  may  make  1 lb.=y^-o 
of  an  inch,  so  that  a line  c d , fig.  10, 1 inch  long  will  represent  the  force  or 


Fig.  10.  Force  Represented  by  a Line. 


strain  which  the  horse  is  exerting  on  the  rope.  Or,  taking  the  illustration 
of  the  boat  in  fig.  6,  it  may  be  supposed  that  the  person  rowing  it  exerts  a 
force  of  24  lbs.,  while  the  current  of  the  river  is  equal  to  18  lbs.  This  dia- 
gram has  been  drawn  so  that  one-sixteenth  of  an  inch  is  equal  to  one 
pound.  The  line  A B is  therefore  1^  inches  long,  and  AC  1^  inches  long.  If 
the  parallelogram  is  completed  the  length  of  the  diagonal  A D will  then 
represent  the  resultant  of  the  two  forces,  or  their  combined  effect  on  the 
boat  in  the  direction  A D. 

From  what  has  been  said,  it  will  be  seen  that  a line  may  be  made  to 
represent  the  magnitude  of  a force,  and  also  the  direction  in  which  it  is  ex- 
erted. Thus,  in  fig.  9 the  line  a b represents  a force  which  is  exerted  down- 
ward ; in  fig.  10  the  force  represented  by  c d is  exerted  horizontally,  or 
nearly  so,  and  in  fig.  8 A B acts  diagonally.  Therefore  it  is  plain  that  the 
length  and  position  of  a line  may  be  made  to  represent  any  magnitude  and 
direction  of  a force. 

Question  89.  Does  the  principle  of  the  composition  of  motion  apply  to 
forces  or  strains  exerted  by  bodies  at  rest  ? 

Answer.  Yes. 

Question  40.  How  can  we  show  this  experimentally  ? 

Answer.  If  we  will  suspend  a weight  W,  fig.  11,  equal,  say,  to  10  lbs.,  by 


16 


Catechism  of  the  Locomotive. 


two  inclined  cords  b f and  b g,  which  pass  over  pulleys / and  g,  it  will  be 
found  that  the  weights  A and  B,  which  will  balance  W,  can  be  determined 
as  follows : As  the  force  exerted  by  the  weight  W acts  downward,  its  di- 


Fig.  11.  Diagram  of  Composition  of  Forces. 


rection  is  represented  by  the  perpendicular  line  b c.  If  now  we  lay  off  the 
distance  be  to  any  convenient  scale,  say  £ inch=l  lb.,  to  represent  the 
'weight  W,  and  then  draw  the  lines  c d and  c e parallel  to  b f and  b g,  then 
c d or  e b will  represent  the  strain  on  the  cord  b f and  c e,  or  d b will  repre- 
sent that  on  b g,  and  they  will  be  .equal  to  the  weights  A and  B , which 
will  balance  IV.  Hence,  we  see  again  that  the  resultant  of  two  forces 
is  the  diagonal  of  a parallelogram,  the  sides  of  which  represent  the  direc- 
tion and  magnitude  of  those  forces. 

Question  41.  What  is  this  process  of  determining  the  direction  and 
magnitude  of  three  or  more  forces  called? 

Answer.  It  is  called  the  “ composition  of  forces ,”  and  a figure  like  c eb  d, 
fig.  11,  is  called  a “ parallelogram  of  forces." 

Question  42.  What  other  illustrations  may  be  given  of  the  application 
of  this  principle  ? 

Answer.  The  strain  on  the  parts  of  a common  crane,  fig.  12,  for  lifting 
heavy  objects  can  be  deduced  in  this  way.  Thus,  let  A represent  the  post, 
B the  jib,  and  c the  tie  rod  of  such  a crane.  If  W equals  1,000  lbs.,  if  we 
make  a £=1,000,  and  draw  b c parallel  to  C,  then  the  length  of  the  line  c b 
will  represent  the  strain  on  the  rod  C and  c a that  on  the  strut  B.  It  will 
be  plain  from  the  figure  and  a little  reflection  that  the  effect  of  the  weight 
W will  be  to  compress  B and  pull  C apart.  Therefore  B is  said  to  be  sub- 
jected to  a strain  of  compression  and  C to  one  of  tension.  If  the  parallelo- 


Resolution  of  Motion  and  Forces. 


17 


gram  of  forces  was  completed  the  line  a d would  be  drawn  parallel  to  C 
and  to  c b , and  b d parallel  to  B or  c a.  In  most  cases  all  that  is  needed 


to  determine  a strain  on  a structure  is  to  draw  a triangle  like  a b c,  which 
is  one-half  of  the  parallelogram  a c b d. 


A roof  or  bridge  truss  like  that  shown  in  fig.  13  is  another  illustration  of 
this  principle.  In  this  R R are  the  timbers  or  rafters,  and  T a tie-rod,  and 
W a weight  resting  on  the  rafters.  One-half  of  this  weight  will  be  carried 
by  each  of  the  rafters  R.  If  then  a b is  made  equal  to  one-half  of  IV,  and 
be  is  drawn  parallel  to  T,  then  a c will  represent  the  strain  on  R and  b c 
that  on  T.  If  the  inclination  of  the  timbers  R R is  the  same,  they  will 
each  be  subjected  to  an  equal  strain,  and  the  foot  of  the  one  will  push 
against  the  tie-rod  with  a force  just  equal  to  that  exerted  by  the  other 
timber  at  the  opposite  end. 


18 


Catechism  of  the  Locomotive. 


QUESTION  43.  Can  the  velocity  in  different  directions  of  a moving  body 
also  be  represented  by  a parallelogram  ? 

Answer.  Yes,  this  is  shown  in  fig.  5 in  the  case  of  the  billiard-ball  and 
elevator.  Here  the  ball  b had  a velocity  of  4 feet  per  second  in  the  direc- 
tion of  the  horizontal  line  b c,  and  a vertical  velocity  of  6 feet  per  second, 
as  shown  by  the  line  b b'.  If  it  is  moved  simultaneously  at  these  velocities 
and  in  the  directions  indicated  by  the  lines,  then,  as  was  shown,  it  will 
move  in  a direction  and  a distance  equal  to  the  length  of  the  line  b c'  in 
the  same  period  of  time ; b c'  will  therefore  represent  the  velocity  of  the 
ball  under  the  combined  action  of  the  horizontal  and  vertical  velocities. 

On  the  other  hand,  if  we  know  the  velocity  at  which  the  ball  moves  in 
the  direction  b d,  and  wish  to  ascertain  the  speeds  at  which  it  moves 
horizontally  and  vertically,  all  we  need  do  is  to  draw  a parallelogram 
whose  sides  represent  the  direction  of  the  velocity  which  we  want  to  as- 
certain.* 


* The  principle  of  the  resolution  of  motion,  forces  and  velocities  has  a direct  application  to 
the  action  of  the  piston,  connecting-rod  and  crank,  which  is  discussed  in  chapter  IX. 


CHAPTER  III. 

THE  PRINCIPLES  OF  THE  LEVER.* 

Question  44.  How  may  the  principle  of  the  lever  be  explained? 

Answer.  Every  boy  has  learned  that  if  the  middle  of  a board  rests  on 
a fence-rail  or  other  support  that  two  boys,  of  equal  weight,  will  balance 
each  other,  if  one  of  them  sits  on  one  end  of  the  board  and  one  on  the 
other  end.  If  it  is  12  feet  long,  and  is  moved  so  that  the  support  is  4 feet 
from  one  end  and  8 feet  from  the  other,  then  the  boy  who  sits  on  the  short 
end  must  be  twice  as  heavy  as  the  one  on  the  long  end  to  balance  the 
other.  If  the  support  is  8 feet  from  one  end  and  9 feet  from  the  other,  as 
in  fig.  14,  then  the  heavy  boy  must  be  three  times  the  weight  of  the  small 
one.  That  is,  if  the  small  boy  weighs  40  lbs.  the  big  one  must  weigh  120 
lbs.  It  is  also  obvious  that  the  weight  of  both  boys  is  sustained  by  the 
support  B,  and  therefore  the  load  on  it  is  equal  to  40  + 120=160,  leaving 
out  the  weight  of  the  board.  It  will  also  be  noticed  that  the  weight  of 
both  boys  bears  downward  on  the  board,  and  if  the  edge  of  the  support  B 
was  sharp  and  hard,  and  the  board  soft,  that  an  indentation  in  it  would  be 
made  where  it  rests  on  the  support,  showing  that  the  pressure  against  the 
board  at  this  point  is  in  an  upward  direction. 

The  same  principle  would  be  illustrated  if  the  board  was  used  as  a lever 
to  lift  a heavy  stone  or  other  object,  as  shown  in  fig.  15.  In  this  case  if 
the  stone  weighed  120  lbs.  and  the  two  arms  of  the  lever  were  the  same 
length  as  before,  it  would  require  a pressure  of  40  lbs.  at  A to  balance  or 
raise  the  stone  at  C,  and  the  support  or  fulcrum , as  it  is  called,  at  B would 
sustain  a pressure  of  160  lbs.  In  this  case,  too,  the  forces  at  A and  C both 
act  downward  and  the  force  against  the  boards  is  upward,  as  indicated  by 
the  arrows. 

If  we  place  the  support  at  C,  as  in  fig.  16,  and  the  stone  at  B,  then  an 
upward  force  of  40  lbs.  exerted  at  A will  raise  a stone  of  160  lbs.  weight  at 
B.  In  this  case  the  two  forces  at  A and  C both  act  upward,  and  that  at  B 
downward,  as  indicated  by  the  arrows. 


* The  principles  explained  in  this  chapter  are  applied  in  succeeding  parts  of  the  book,  but 
especially  in  the  chapters  relating  to  brakes. 


20 


Catechism  of  the  Locomotive. 


If  the  support  or  fulcrum  against  which  the  board  bears  is  placed  above 
it  at  A,  and  if  the  stone  is  at  the  end  C,  as  show  in  fig.  17,  and  the  person 
should  take  hold  of  the  board  at  B,  then  it  would  require  an  upward  pull 
of  160  lbs.  at  B to  raise  the  stone,  and  the  forces  would  act  in  the  direc- 
tion indicated  by  the  arrows. 


From  these  illustrations  it  will  be  seen  that  in  each  case  when  the  levers 
are  in  equilibrium  or  are  balanced,  there  are  two  forces  which  act  in  one 
direction  against  the  ends  of  the  lever , and  one  force  which  acts  in  the  oppo- 
site direction  between  them , and  that  the  two  end  forces  added  together  or 
their  sum  is  equal  to  the  third  force  acting  in  the  opposite  direction . This 
is  true  not  only  of  the  cases  illustrated,  but  it  is  true  of  all  levers  on  which 


The  Principles  of  the  Lever. 


21 


the  forces  act  in  directions  parallel  to  each  other,  which  are  the  only  kind 
which  need  be  considered  here.  The  greater  of  the  two  forces  which  act 
in  the  same  direction  and  is  exerted  on  the  short  end  of  the  lever  will  be 
called  the  major-force,  the  smaller  one,  which  acts  on  the  long  end  of  the 
lever,  the  minor-force,  and  that  acting  in  the  opposite  direction  between 
the  two  ends  the  counter-force.  The  major-force  is  always  at  the  short 
end  of  the  lever,  and  the  minor-force  at  the  long  end.  If  the  two  arms  of 
the  lever  are  of  equal  length,  the  major  and  minor-forces  will  also  be 


equal.  If  the  major-force  is  multiplied  by  the  length  of  the  short  arm  of 
the  lever,  the  product  will  always  be  equal  to  that  of  the  minor-force  multi- 
plied by  the  length  of  the  long  end  of  the  lever.  That  is,  in  fig.  14  the 
weight  of  the  major  boy,  C=120  lbs.,  multiplied  by  3 feet  (the  length  of 
the  short  end  C i?)=360,  and  the  weight  of  the  minor  boy,  A =40  lbs.  x 9 
feet  (the  length  of  the  long  end,  A B)  also=360. 

It  does  not  make  any  difference,  either,  in  what  direction  these  forces 
act.  The  effect  of  their  action  will  be  the  same,  if  instead  of  being  hori- 
zontal the  levers  stood  upright  or  vertical,  as  shown  in  figs.  18-20,  in 
which  the  direction  of  the  forces  is  indicated  by  darts  and  their  magni- 
tude by  figures.  These  figures  show,  too,  that  the  action  of  the  forces  in 
figs.  18  and  20  is  exactly  the  same,  and  that  the  only  difference  between 


92 


Catechism  of  the  Locomotive. 


them  and  fig.  19  is  that  the  forces  in  the  two  cases  act  in  opposite  direc- 
tions. 

Question  45.  How  can  we  know  which  is  the  major , which  the  minor, 
and  which  the  counter -force  acting  on  a lever? 

Answer.  This  can  always  be  known  with  certainty  if  it  is  remembered 
that  the  major  and  minor-forces  always  act  on  the  ends  of  the  lever  and  in 
an  opposite  direction  to  the  counter-force  * which  is  between  them,  and 
that  the  major-force  is  always  at  the  short  end  of  the  lever  and  the  minor 
one  at  the  long  end. 

Question  46.  If  we  have  the  length  of  the  two  ends  of  a lever  and 
either  the  major  or  the  minor-force,  how  can  we  calcidate  the  other  ? 

Answer.  Multiply  the  known  force  by  the  length  of  its  end 

OF  THE  LEVER  AND  DIVIDE  THE  PRODUCT  BY  THE  LENGTH  OF  THE  OPPO- 
SITE end.  The  quotent  will  be  the  required  force.  Thus,  supposing  that 
in  fig.  14  we  have  the  weight  of  the  small  boy,  40  lbs.,  and  the  length  of 
the  two  ends  of  the  lever  as  9 and  3 feet  respectively,  then  40  x 9^3=120 
=the  major  force  at  C. 

Question  47.  If  we  have  the  length  of  the  two  ends  of  a lever  and 
either  the  major  or  the  minor-force,  how  can  we  calculate  the  counter-force  ? 

Answer.  Add  the  length  of  the  two  ends  of  the  lever 

TOGETHER  TO  GET  ITS  WHOLE  LENGTH  ; THEN  MULTIPLY  THE  KNOWN 
FORCE  BY  THE  WHOLE  LENGTH  AND  DIVIDE  BY  THE  LENGTH  OF  THE  END 
OF  the  lever  opposite  TO  the  known  force.  Thus,  in  fig.  14,  know- 
ing the  weight  of  the  small  boy  at  A,  and  the  length  of  the  two  ends  of 
the  lever  being  3 and  9 feet,  then  3 + 9=12  x40-r-3=160=counter-force  at 
B. 

Question  48.  If  we  have  the  counter-force  and  the  length  of  the  two 
ends  of  the  lever,  how  can  we  calculate  the  major  and  minor-forces  ? 

Answer.  To  get  the  major-force,  multiply  the  counter-force 

BY  THE  LENGTH  OF  THE  LONG  END  OF  THE  LEVER  AND  DIVIDE  BY  ITS 
WHOLE  LENGTH  ; TO  GET  THE  MINOR-FORCE,  MULTIPLY  THE  COUNTER- 
FORCE BY  THE  LENGTH  OF  THE  SHORT  END  OF  THE  LEVER  AND  DIVIDE 

by  its  whole  length.  Thus,  if  in  fig.  16  we  have  B,  the  counter-force 
equal  to  160  lbs.,  and  the  two  arms  of  the  lever  3 and  9 feet  respectively, 
then  160  x 9-f-12=120=major-force,  or  160  x 3 -f-12 =40= minor-force. 

QUESTION  49.  Having  the  major  and  minor-forces  which  are  exerted 

* The  direction  in  which  a force  acts  on  a lever  can  always  be  known  by  observing  which  side 
of  the  lever  would  be  indented  if  it  was  made  of  soft  material  and  the  force  was  exerted  against 
it  by  a sharp  object. 


The  Principles  of  the  Lever. 


23 


at  the  ends  of  a lever , and  its  whole  length , how  can  we  calculate  the  length 
of  its  two  ends  ? 

Answer.  First,  add  the  major  and  minor-forces  together, 

WHICH  WILL  GIVE  THE  COUNTER-FORCE  ; THEN  TO  GET  THE  LENGTH  OF 
THE  LONG  END  OF  THE  LEVER  MULTIPLY  THE  MAJOR-FORCE  BY  THE 
WHOLE  LENGTH  AND  DIVIDE  BY  THE  COUNTER-FORCE.  TO  GET  THE 
LENGTH  OF  THE  SHORT  END,  MULTIPLY  THE  MINOR-FORCE  BY  THE 
WHOLE  LENGTH  AND  DIVIDE  BY  THE  COUNTER-FORCE.  OR  IF  WE  HAVE 
THE  LENGTH  OF  ONE  END  WE  CAN  GET  THAT  OF  THE  OTHER  BY  DEDUCT- 
ING THE  LENGTH  OF  THE  ONE  FROM  THE  WHOLE  LENGTH. 

Thus,  supposing  that  in  fig.  16  the  major  and  minor-forces,  A and  C,  are 
equal  to  120  and  40  lbs.  respectively,  and  the  whole  length  of  the  lever  12 
feet,  then  120  + 40=160=counter-force,  and  120  x 12-j-160=9=length  of 
long  end  of  lever,  and  40  x 12-s-160=3=length  of  short  end  of  lever. 


CHAPTER  IV. 


THE  FORCES  OF  AIR  AND  STEAM. 

QUESTION  50.  What  is  meant  by  the  pressure  of  the  air  ? 

Answer.  It  is  the  force  exerted  by  the  weight  of  the  air  on  every  point 
with  which  it  is  in  contact.  The  globe  of  the  earth  is  surrounded  by  a 
layer  of  air  about  50  miles  thick,  and,  like  every  other  substance,  the  air 
possesses  weight,  and  hence,  presses  upon  every  object  with  which  it  is  in 
contact. 

Question  51.  How  can  it  be  shown  that  air  possesses  weight? 

Answer.  By  weighing  a glass  flask  when  it  is  filled  with  air,  and  again 
when  the  air  is  exhausted  from  it.  In  the  latter  condition  the  weight  of  the 
flask  will  be  found  to  be  sensibly  less  than  it  was  when  full  of  air,  show- 
ing that  the  air  which  the  flask  contained  when  it  was  first  weighed 
increased  its  weight. 

Question  52.  Why  do  we  not  feel  this  pressure  on  our  bodies? 

Answer.  Because  the  air  surrounds  us  on  all  sides,  and  presses  just  as 
much  in  one  direction  as  it  does  in  another,  so  that  the  pressures  in  dif- 
ferent directions  just  balance  each  other,  or  are  in  equilibrium  ; but  if  the 
air  presses  on  one  side  only  of  an  object  as  it  does  when  you  suck  the  air 
from  a tube  closed  at  one  end  and  you  cover  the  open  end  with  your 
tongue,  the  air  then  presses  your  tongue  against  the  tube,  and  the  one 
appears  to  adhere  to  the  other ; or  if  the  air  be  sucked  out  of  a tube  one 
end  of  which  is  inserted  in  a liquid,  the  latter  will  be  forced  up  the  tube. 
A piece  of  thick  leather  under  ordinary  conditions  will  not  adhere  to  any- 
thing, but  if  it  be  thoroughly  wet  and  pressed  hard  against  the  surface  of 
a smooth  stone,  so  as  to  force  out  the  air  from  under  it,  the  stone,  as  nearly 
all  school-boys  know,  can  be  lifted  up  if  a string  is  attached  to  the  leather. 
These  phenomena  are  due  to  the  pressure  of  the  atmosphere ; in  the  first 
case  on  one  side  of  the  person’s  tongue,  pressing  it  against  the  mouth  of 
the  tube ; in  the  second,  to  the  weight  of  the  air  pressing  on  the  surface 
of  the  liquid,  forcing  it  into  the  vacuum  in  the  tube,  and  in  the  last,  to 
the  same  pressure  on  the  top  of  the  leather,  causing  it  to  adhere  to  the 
stone. 


The  Forces  of  Air  and  Steam. 


25 


QUESTION  53.  What  is  the  amount  of  the  pressure  of  the  atmosphere , 
and  how  is  it  measured? 

Answer.  It  is  usually  measured  by  the  pressure  on  one  square  inch  of 
surface,  which,  at  the  earth’s  surface,  is  15  pounds.*  If,  for  example,  we 
have  a cylinder,  A,  fig.  21,  with  an  air-tight  piston,  B , fitted  to  it,  whose 
area  is  just  one  square  inch,  and  through  the  tube,  C,  we  exhaust  the  air  from 
the  cylinder  above  the  piston,  the  air  will  press  against  the  under  side  of 
the  piston  so  that,  if  no  power  is  required  to  overcome  its  friction  in  the 
cylinder,  the  pressure  of  the  air  will  raise  a weight  of  15  pounds.  The 
pressure  of  air  varies,  however,  as  you  ascend  or  descend  from  the  surface 
of  the  earth,  because  as  you  go  up  on  a mountain  or  in  a balloon  the  layer 
of  air  above  you  becomes  thinner,  and,  therefore,  its  weight  and  conse- 
quent pressure  are  diminished  ; and  as  you  descend,  as  in  a deep  mine, 
the  layer  is  thicker,  and  its  pressure  is  consequently  greater. 


Fig.  21.  Weight  Raised  by  Pressure  of  Air  below  Piston.  Scale  3 in.=l  ft. 

Question  54.  What  is  steam  ? 

Answer.  In  the  dictionary,  steam  is  defined  as  “ the  elastic,  aeriform 
fluid  into  which  water  is  converted,  when  heated  to  the  boiling-point,”  or, 
in  other  words,  steam  is  water  changed  by  means  of  heat  into  a gas.  It  is 
the  transparent  fluid  which  escapes  from  the  mouth  of  a tea-kettle  when 


* In  common  practice  it  is  generally  taken  at  15  lbs.  per  square  inch,  but  the  average  atmos- 
pheric pressure  at  the  level  of  the  sea  is,  more  accurately,  14.7  pounds. 


Catechism  of  the  Locomotive. 


26 


the  water  in  it  is  boiling.  The  visible  cloud  which  escapes  from  boiling 
water  and  is  seen  in  the  form  of  mist  at  the  mouth  of  the  exhaust-pipe  of 
a steam  engine  is  not  true  steam.  It  is  rather  small  particles  of  water, 
into  which  the  steam  has  condensed  through  contact  with  the  cold  air. 
True  steam  is  invisible,  as  we  may  observe  near  the  mouth  of  a kettle  or 
the  exhaust-pipe  of  an  engine  from  which  we  know  it  is  escaping.  At 
every  temperature  there  is  formed  from  water,  on  its  surface,  vapor  of 
which  the  clouds  are  formed  at  all  seasons  of  the  year.  This  change  of 
water  into  vapor,  or  evaporation  of  water,  take  splace  at  low  temperatures 
only  on  its  surface,  however.  But  if  we  heat  water  in  a vessel  to  a tem- 
perature of  212  degrees  Fahrenheit,  then  the  inner  particles  of  the  mass  of 
water  (lying  on  the  heating  surface  of  the  vessel)  are  changed  into  steam, 
and  rise  to  the  surface  in  bubbles,  which  is  the  phenomenon  we  call 
boiling. 

QUESTION  55.  If  water  is  heated  in  an  open  vessel,  what  occurs? 

Answer.  It  continues  for  some  time  to  increase  in  temperature,  and 
the  evaporation  becomes  more  and  more  rapid.  At  length  bubbles  of 
vapor  break  out  and  reach  the  surface,  and  the  process  of  boiling  or  ebulli- 
tion has  begun.  When  this  takes  place,  the  temperature  of  the  water 
ceases  to  rise,  and  it  remains  stationary  until  all  the  water  has  boiled  away, 
the  only  difference  being  that  if  the  supply  of  heat  be  very  great  the  pro- 
cess is  very  rapid,  and  if  the  supply  of  heat  be  small  the  process  is  very 
slow.  The  point  at  which  ebullition  commences  is  called  the  boiling 
Point. 

QUESTION  56.  On  what  does  the  boiling  point  depend? 

Answer.  Chiefly  on  the  pressure  on  the  surface  of  the  water,  but  to 
some  extent  upon  the  purity  of  the  water.  Thus,  boiling,  which  takes 
place  at  212  degrees  under  the  ordinary  atmospheric  pressure,  in  lighter 
air,  as  on  high  mountains,  takes  place  at  a much  lower  temperature  than 
on  lowlands,  and  water  will  boil  in  a glass  tube  from  which  the  air  has 
been  exhausted  by  the  warmth  of  the  hand,  that  is,  at  92  degrees. 

QUESTION  57.  What  is  the  pressure  of  stea?n  which  escapes  from  boiling 
water  in  an  open  vessel? 

Answer.  It  is  exactly  equal  to  the  pressure  of  the  atmosphere  in  which 
it  is  boiled.  Ordinarily,  this  is  about  15  lbs.,  and  the  boiling-point  212 
degrees ; but  if  we  go  up  on  a mountain  where  the  atmospheric  pressure 
is  only  10  lbs.  per  square  inch,  the  water  will  then  boil  at  a temperature  of 
193.3  degrees,  and  the  steam  which  escapes  will  have  the  same  pressure  as 
the  atmosphere,  or  10  lbs.  per  square  inch.  On  the  other  hand,  if  we 


The  Forces  of  Air  and  Steam. 


37 


could  go  down  into  a mine  where  the  atmospheric  pressure  was  20  lbs,  per 
square  inch,  the  water  would  not  boil  until  it  was  heated  to  228  degrees, 
and  the  pressure  of  the  escaping  steam  would  then  be  20  lbs.  per  square 
inch. 

Question  58.  If  water  is  boiled  in  an  enclosed  vessel,  like  a covered  tea- 
kettle or  a steam-boiler,  what  occurs  ? 

Answer.  The  steam  rises  and  fills  the  space  above  the  water,  and,  if  it 
cannot  escape,  increases  in  pressure.  The  temperature  of  both  the  water 
and  the  steam  rises  with  the  pressure,  and  will  continue  to  do  so  as  long 
as  the  heat  is  increased,  or  until  the  steam  can  escape,  or  the  vessel  is 
exploded.  The  boiling-point  also  rises  as  the  steam  pressure  increases. 

Question  59.  How  can  this  effect  be  illustrated ? 

Answer.  It  can  be  shown  if  we  take  a glass  tube,  T,  fig.  22,  closed  at 
its  lower  end,  and  put  a small  quantity  of  water  in  it,  and  then  force  a 
cork,  C,  which  fits  the  tube,  or  a wad  of  cotton  saturated  with  tallow, 
down  on  top  of  the  water,  and  then  hold  the  lower  end  of  the  tube  over  a 
spirit  lamp  or  gas  flame,  and  heat  it  slowly,  so  as  not  to  crack  the  glass 


tube  Bubbles  of  steam  will  then  form  at  the  bottom  of  the  water,  as 
shown  in  fig.  23.  These  will  rise  to  the  top,  and  will  soon  force  the  cork 


28 


Catechism  of  the  Locomotive. 


or  wad  of  cotton  upward  with  more  or  less  violence,  in  proportion  to  the 
tightness  with  which  it  fits  the  tube,  and  the  rate  at  which  the  water  is 
boiled. 

QUESTION  60.  Is  there  any  pressure  which  corresponds  to  the  tempera- 
ture of  steam  and  water  ? 

Answer.  Yes.  There  is  a fixed  pressure  for  every  temperature,  when 
steam  is  in  contact  with  water,  and  its  pressure  cannot  be  increased  or 
diminished  without  at  the  same  time  heating  or  cooling  the  water,  and 
the  higher  the  temperature  of  the  water  the  greater  will  be  the  correspond- 
ing steam  pressure.  Thus  water  at  212  degrees  produces  steam  with  a 
pressure  equal  to  that  of  the  atmosphere ; at  240  degrees,  the  steam  will 
have  a pressure  of  25  lbs.  per  square  inch,  or  10  lbs.  more  than  the  atmos- 
pheric pressure ; at  281  degrees,  a pressure  of  50  lbs. ; and  at  328  degrees, 
100  lbs.  As  this  relation  of  pressure  to  temperature  is  fixed,  if  we  know 
the  one  we  can  tell  the  other.  This  is  true,  however,  only  where  the  steam 
is  in  contact  with  water,  when  it  is  called  saturated  steam.  If  it  is  sepa- 
rated from  water,  it  may  be  heated  to  a higher  temperature  without  increas- 
ing its  pressure  in  the  same  proportion,  and  it  is  then  called  superheated 
steam.  The  temperature  of  steam  at  different  pressures  is  given  in  a 
table  in  an  appendix. 

Question  61.  How  is  the  pressure  of  steam  measured? 

Answer.  In  the  same  way  as  that  of  the  atmosphere — that  is,  by  the 
force  exerted  on  one  square  inch  of  surface.  Thus,  if  steam  is  admitted 
into  the  cylinder,  A,  fig.  24,  under  the  piston,  B,  whose  area  is  equal  to  one 
square  inch  of  surface — supposing,  as  we  did  before,  that  no  power  is 
required  to  overcome  its  friction  in  the  cylinder — then,  if  the  pressure  of 
the  steam  thus  admitted  below  the  piston  would  just  balance  the  pressure 
of  the  atmosphere  above  it,  the  steam  pressure  would  be  equal  to  15  lbs. 
If,  besides  overcoming  the  pressure  of  the  atmosphere,  the  steam  below 
the  piston  would  raise  a weight,  W,  of  15  lbs.,  then  its  pressure  per  square 
inch  would  in  reality  be  equal  to  30  lbs.  per  square  inch.  If  the  pressure 
of  the  atmosphere  is  included  or  added  to  that  of  steam  above  it,  it  is  called 
its  absolute  pressure.  In  ordinary  high-pressure  steam  engines,  however, 
the  steam  must  always  overcome  the  pressure  of  the  atmosphere,  and 
therefore  the  only  part  of  the  pressure  which  is  effective  is  that  above,  or 
by  which  it  exceeds,  the  atmospheric  pressure.  This  is  therefore  called 
the  effective  or  working  pressure.  For  example,  although  the  steam 
admitted  under  the  piston  in  fig.  24  has  an  absolute  pressure  of  30  lbs.  per 
square  inch,  yet  it  will  only  raise  a weight  of  15  lbs.,  because  it  must  first 


The  Forces  of  Air  and  Steam. 


29 


overcome  the  pressure  of  the  air  on  the  other  side  of  the  piston.  The 
pressure  of  the  steam  used  in  most  stationary  and  in  locomotive  engines 
is,  therefore,  measured  by  its  pressure  above  the  atmosphere.  That  is,  if 
steam  introduced  under  the  piston  in  fig.  24  will  raise  a weight  of  only  10 


Fig.  24.  Weight  Raised  by  Pressure  of  Steam  below  Piston.  Scale  3 in.=l  ft. 

lbs.,  we  say  it  has  a pressure  of  15  lbs.  per  square  inch  ; if  it  will  raise  50 
lbs.,  its  pressure  is  said  to  be  50  lbs.  per  square  inch,  and  so  on.  The 
pressure  of  the  atmosphere  is  disregarded,  and  all  steam-gauges  used  on 
locomotives  are  graduated  in  that  way.  In  speaking  of  steam  pressure  in 
future,  therefore,  unless  otherwise  specified,  we  shall  mean  effective  or 
working  and  not  absolute  pressure. 

Question  62.  What  is  meant  by  the  expansion  of  steam  ? 

Answer.  In  all  gases  a repulsion  is  exerted  between  the  various  parti- 
cles, so  that  any  gas,  however  small  in  quantity,  will  always  fill  the  vessel 
in  which  it  is  held.  Steam  possesses  this  same  property,  and,  if  placed  in 
any  vessel,  the  particles  in  endeavoring  to  separate  from  each  other  will 
exert  a force  on  all  its  sides.  This  force  we  call  the  steam  pressure.  To 
illustrate  this  we  will  suppose  that  the  cylinder,  A,  in  fig.  24,  is  half  filled 
with  steam  of  80  lbs.  pressure.  If,  now,  the  supply  of  steam  is  shut  off, 
the  steam  in  the  cylinder  if  the  weight,  W,  is  reduced,  will  expand  so  as 
to  push  the  piston  upward,  but  with  a somewhat  diminishing  force,  the 
nature  of  which  will  be  explained  hereafter. 


30 


Catechism  of  the  Locomotive. 


Question  63.  What  is  meant  by  the  “ volume  ” of  air  or  steam? 

Answer.  It  means  the  space  which  it  fills  or  occupies. 

Question  64.  What  is  the  proportion  which  exists  between  the  volume 
and  the  pressure  of  air,  steam  or  other  gas? 

Answer.  As  long  ago  as  1662,  Robert  Boyle,  from  experiments  “touch- 
ing the  spring  of  air,”  discovered  the  law  which  has  since  been  called 
“ Boyle's  law,"  that  “ the  pressure  of  a portion  of  gas  at  a constant  tempera- 
ture varies  inversely  as  the  space  it  occupies  that  is,  the  one  increases  in 
the  same  proportion  as  the  other  diminishes.  If  we  admit  steam  of  30  lbs. 
absolute  pressure  per  square  inch  into  the  cylinder,  A,  fig.  24,  and  then  cut 
off  the  supply  by  closing  the  cock,  C,  and  allow  the  steam  in  the  cylinder 
to  expand  to  double  its  volume  by  pushing  the  piston  to  the  end  of  the 
cylinder,  the  steam  pressure  will  then  be  only  15  lbs. ; if  it  should  expand 
to  three  times  its  volume  its  pressure  would  be  only  one-third,  or  10  lbs. 
per  square  inch.  This  method  for  calculating  the  pressure  of  steam  after 
it  has  expanded,  is  correct  only  for  the  absolute  and  not  for  the  effective 
pressures  of  steam.  In  order  to  ascertain  the  effective  pressures  of  steam 
after  expansion,  it  is  only  necessary  to  make  the  calculation  with  the 
absolute  pressure  and  deduct  the  atmospheric  pressure  from  the  result. 
If,  after  being  thus  expanded,  the  piston  be  pushed  down  again  so  as  to 
compress  the  steam  into  its  original  space,  its  pressure  will  again  be  30 
lbs.,  providing  no  heat  has  been  lost  in  any  way. 

Question  65.  How  can  we  determine  approximately  the  pressure  of 
steam,  air  or  gas  after  it  has  been  compressed  or  expanded? 

Answer.  By  multiplying  its  absolute  pressure  per  square 

INCH  BY  ITS  VOLUME  BEFORE  IT  IS  COMPRESSED  OR  EXPANDED,  AND 
THEN  DIVIDING  THE  PRODUCT  BY  ITS  VOLUME*  AFTER  IT  IS  EXPANDED 
or  compressed.  Thus,  if  we  had  a cylinder  whose  piston  moves  24 
inches,  if  8 inches  of  its  length  was  filled  with  steam  of  an  absolute 
pressure  of  90  lbs.,  and  it  was  expanded  so  as  to  fill  the  whole  cylinder, 
the  calculation  to  ascertain  its  pressure  after  expansion  would  be  as  follows: 

90x8 

=30  lbs.  final  pressure. 

24 

If  10,  12  and  15  inches  of  the  cylinder  was  filled  with  steam  and  ex- 

* The  volume  may  be  taken  in  cubic  inches,  cubic  feet  or  in  the  number  of  inches  in  the 
length  of  a cylinder  which  is  occupied  by  the  steam,  air  or  gas  ; but  the  same  unit  of  measure- 
ment must  be  used  for  both  the  multiplier  and  the  divisor. 


The  Forces  of  Air  and  Steam. 


31 


panded  to  its  full  volume,  the  final  pressures  would  be  37i,  45  and  56^  lbs., 
respectively.  To  get  the  effective  pressures,  deduct  the  atmospheric  pres- 
sure from  these  figures. 

Question  66.  What  is  the  proportion  between  the  volume  of  steam  and 
that  of  the  water  from  which  it  is  formed? 

Answer.  At  the  pressure  of  the  atmosphere  (15  lbs.  'per  square  inch) 
each  cubic  inch  of  water  will  make  1,610  cubic  inches  of  steam.  At  double 
that  pressure,  or  30  lbs.  absolute  pressure,  it  will  make  a little  more  than 
half  as  much,  or  838  cubic  inches ; at  four  times,  or  60  lbs.  absolute  pres- 
sure, 437  cubic  inches,  or  a little  more  than  a fourth  as  much  as  at  the 
pressure  of  the  atmosphere. 

Question  67.  Why  is  it  that  the  quantity  of  steam  at  high  pressure  is 
somewhat  greater  than  in  inverse  proportion  to  the  pressure? 

Answer.  Because  the  boiling-point  of  water,  as  has  already  been  ex- 
plained, is  higher  as  the  pressure  increases,  and  therefore  the  temperature 
of  the  steam  produced  at  such  pressure  is  also  higher  than  at  lower  pres- 
sures ; and,  as  all  gases  are  expanded  by  heat,  therefore  the  volume  of 
steam  at  the  higher  pressures  is  somewhat  greater  than  in  inverse  propor- 
tion to  its  pressure,  on  account  of  being  somewhat  expanded  by  its  high 
temperature.  To  make  this  plain,  if  we  take  a cubic  inch  of  water  and 
convert  it  into  steam  of  atmospheric  pressure,  its  volume  will  be  1,610 
times  that  of  the  water  and  its  temperature  212  degrees.*  If  we  convert 
this  quantity  of  water  into  steam  with  a pressure  double  that  of  the  atmos- 
phere, the  volume  of  the  steam  will  be  838  times  that  of  the  water  and  its 
temperature  will  be  250.4  degrees.  If  the  volume  of  the  steam  were  ex- 
actly inversely  proportional  to  the  pressure,  the  cubic  inch  of  water  at 
double  the  atmospheric  pressure  would  make  only  805  cubic  inches  of 
steam ; but,  as  the  boiling-point  at  that  pressure  is  38.4  degrees  higher,  the 
steam  is  expanded  33  cubic  inches  by  the  increase  of  its  heat  due  to  the 
higher  boiling-point. 

Question  68.  What  is  meant  by  the  condensation  of  steam  ? 

Answer.  It  is  the  reconversion  of  steam  into  water  by  cooling  it,  or 
depriving  it  of  part  of  its  heat.  It  has  been  shown  that  the  temperature 
of  water  must  be  raised  to  a certain  point  to  generate  steam  of  a given 
pressure.  If  the  process  is  reversed,  and  we  deprive  the  steam  of  a part 
of  its  heat,  some  of  the  steam  is  then  at  once  reconverted  into  water,  or 
condensed,  and  the  pressure  of  that  which  remains  will  be  reduced  just  in 
proportion  as  the  heat  is  lost.  When  the  temperature  gets  below  212 


* More  accurately,  213.1  degrees,  if  we  call  the  atmospheric  pressure  15  lbs. 


32 


Catechism  of  the  Locomotive. 


degrees  under  atmospheric  pressure,  all  the  steam  will  be  condensed.  As 
the  useful  work  which  steam  can  do  in  an  engine  is  due  to  its  pressure, 
which,  in  turn,  depends  on  its  temperature,  any  loss  of  heat  will  diminish 
its  effective  power.  For  this  reason,  all  waste  of  heat  from  a steam  engine 
should,  as  far  as  possible,  be  prevented. 

Question  69.  How  is  the  heat  of  the  steam  wasted  or  lost  in  an  ordi- 
nary steam  engine  ? 

Answer.  It  is  wasted  in  three  ways:  First,  by  conduction;  second,  by 
convection  ; and  third,  by  radiation. 

Question  70.  What  is  meant  by  these  three  terms? 

Answer.  (1.)  By  conduction  is  meant  that  phenomenon  which  is  mani- 
fested when  we  put  one  end  of  a metal  bar,  two  or  three  feet  long,  into  the 
fire  and  heat  it.  The  heat  is  then  gradually  conveyed  from  one  particle 
of  the  metal  to  that  next  to  it  until  finally  the  end  of  the  bar  farthest  from 
the  fire  may  become  so  hot  that  it  cannot  be  touched.  The  heat  is  then 
said  to  be  conducted  through  the  bar.  In  the  same  way  the  metal  of  the 
boiler,  pipes,  cylinders  and  other  parts  of  the  engine  becomes  heated  on 
one  side,  and  the  heat  is  thus  conveyed  to  the  outside  of  these  parts. 

(2.)  The  air  with  which  they  are  surrounded  then  becomes  heated,  and, 
being  then  lighter  than  the  cold  air,  it  rises  and  is  again  replaced  with  air 
which  is  not  heated.  In  this  way  the  heat  is  conveyed  away  by  the  air,  and 
this  phenomenon  is  therefore  called  convection. 

(3.)  If  an  iron  plate  be  placed  in  front  of  an  ordinary  grate  fire,  three 
or  four  feet  from  it  and  exposed  to  the  rays  of  heat  from  the  fire,  it  will 
soon  become  so  hot  that  you  cannot  bear  your  hand  on  it.  If  you  place 
your  hand  between  the  iron  plate  and  the  fire  you  will  find  that  only  the 
side  of  your  hand  which  is  exposed  to  the  fire  will  become  hot ; showing 
that  the  air  between  the  plate  and  the  fire  is  not  nearly  so  hot  as  the  plate 
soon  becomes,  and  therefore  that  the  heat  is  not  conveyed  to  the  plate  by 
the  air  between  it  and  the  fire,  but  by  the  heat  rays  from  the  fire.  This 
phenomenon  is  called  radiation.  The  same  thing  occurs  from  any  hot 
body,  as,  for  example,  a coil  of  steam  pipe  for  heating  a room,  a steam 
boiler,  or  cylinder  of  an  engine. 

Question  71.  Is  there  any  difference  in  the  conducting  and  radiating 
power  of  different  substances  ? 

Answer.  Yes,  very  great.  The  difference  in  the  conducting  power  of 
wood  and  iron  is  shown  if  we  place  one  end  of  a bar  of  each  in  the  fire. 
The  wood  will  be  consumed  without  warming  the  bar  more  than  a few 
inches  from  the  fire,  whereas  the  iron  will  soon  become  hot  two  or  three 


The  Forces  of  Air  and  Steam. 


33 


feet  from  the  fire.  Owing  to  the  difference  in  the  conducting  power  of 
cotton  and  wool,  we  wear  cotton  clothing  in  summer  and  woolen  in  winter, 
because  cotton  allows  the  heat  of  the  body  to  be  conducted  away  from  it, 
whereas  woolen  cloth  prevents  to  a great  degree  this  loss  of  heat.  For 
the  same  reason,  the  venders  of  roasted  chestnuts  on  our  streets  wrap  them 
in  a piece  of  blanket  to  keep  them  hot,  that  is,  to  keep  the  heat  in ; and  in 
summer  we  wrap  ice  in  the  same  way  to  keep  it  cold,  that  is,  keep  the 
warmth  of  the  air  out.  The  wool,  being  a very  bad  conductor  of  heat, 
simply  prevents  the  heat  from  being  transferred  from  the  inside  to  the 
outside,  and  vice  versa.  It  is  for  this  reason  that  steam  boilers,  pipes 
and  cylinders  are  nearly  always  covered  with  some  non-conducting  material, 
such  as  wood,  and  sometimes  with  felt. 

The  difference  in  the  radiating  power  of  various  substances  can  be 
shown  if  we  take  a large  thermometer  and  heat  it  up  to  the  temperature 
of  boiling  water.  If  this  thermometer  is  hung  up  in  a room  having  the 
temperature  of  melting  ice,  it  will  loose  in  two  ways — first,  by  heating  the 
air  which  surrounds  it,  that  is,  by  convection,  and  also  by  radiation.  In 
order  to  confine  ourselves  to  the  latter  process,  we  will  suppose  that  the 
chamber  is  a vacuum.  If  we  first  cover  the  bulb  of  the  thermometer  with 
a thin  coating  of  polished  silver,  and  then  ascertain  how  much  heat  it 
radiates  in  a minute,  and  then  coat  it  with  lamp  black  and  repeat  the  same 
experiment — that  is  to  say,  allow  the  thermometer  at  the  boiling-point  to 
cool  for  one  minute  in  a vacuum  chamber  at  the  freezing  point — it  will  be 
found  that  the  thermometer  loses  much  more  in  a minute  when  coated 
with  lamp  black  than  it  did  when  coated  with  silver,  showing  that  much 
more  heat  is  radiated  from  a surface  covered  with  lamp  black  than  from 
polished  silver.  Generally,  it  may  be  stated  that  polished  metals  radiate 
much  less  heat  than  surfaces  which  are  not  polished.*  For  this  reason,  as 
well  as  for  ornament,  locomotive  and  other  boilers  and  cylinders  are  usu- 
ally covered  with  Russia  iron. 

* The  account  of  the  above  experiment  is  copied  from  Balfour  Stewart’s  very  excellent  little 
book,  “ Lessons  in  Elementary  Physics,”  of  which,  and  the  same  author’s  “ Elementary  Treatise 
on  Heat,”  the  writer  nas  made  frequent  use. 


CHAPTER  V. 


ON  WORK,  ENERGY  AND  THE  MECHANICAL  EQUIVALENT  OF  HEAT. 

Question  72.  For  what  purpose  are  all  steam  engines  used? 

Answer.  They  are  used  to  produce  motion,  which  is  opposed  by  some 
resistance.  Thus,  if  an  engine  is  employed  to  raise  grain  from  a railroad 
car  to  the  top  of  a warehouse,  it  must  produce  motion,  which  is  resisted 
by  the  weight  of  the  grain  ; if  it  is  used  to  saw  wood,  it  must  give  motion 
to  the  saw,  which  is  resisted  by  the  fibers  of  the  wood ; a locomotive  en- 
gine must  produce  motion  of  a train  of  cars,  which  is  resisted  by  the  air, 
the  friction  of  the  journals,  and  the  rolling  of  the  wheels  on  the  track ; if 
the  locomotive  is  employed  on  a grade  or  incline,  besides  the  frictional 
resistance  referred  to,  it  must  overcome  that  due  to  its  own  weight  and 
that  of  the  train,  which  is  gradually  lifted  as  it  ascends  the  incline.  In 
producing  motion  opposed  by  some  resistance  an  engine  is  said  to  be  do- 
ing “work.” 

Question  73.  Can  this  work  be  accurately  measured? 

Answer.  Yes ; but  in  order  to  measure  anything  we  must  first  establish 
some  accurate  standard  or  unit  of  measurement.  Thus,  we  say  a bar  of 
iron  is  so  many  inches  long,  or  a road  is  so  many  miles  long.  In  like 
manner  we  speak  of  so  many  seconds,  or  minutes,  or  hours,  or  days,  or 
years,  when  we  speak  of  time.  So  it  is  necessary,  in  order  to  estimate  or 
measure  “ work  ” in  a strictly  scientific  manner,  for  us  to  fix  upon  some 
accurate  standard  or  unit.  In  this  country  and  in  Great  Britain  the  unit 
agreed  upon  for  this  purpose  is  the  amount  of  power  required  to  raise  one 
pound  one  foot,  and  is  called  a foot-pound.  If  we  raise  one  pound  two 
feet  we  do  two  foot-pounds  of  work ; if  three  feet,  three  foot-pounds,  and 
so  on.  Again,  if  we  raise  a weight  of  two  pounds  one  foot  high,  we  like- 
wise do  two  foot-pounds  of  work;  or  if  we  raise  it  two  feet  high,  we  do 
four  foot-pounds,  and  so  on.  In  order  to  determine  the  amount  of  work 
done,  we  must  multiply  the  motion  produced  (in  feet)  by  the  re- 
sistance (in  pounds),  AND  THE  RESULT  WILL  BE  THE  WORK  DONE  IN 
FOOT-POUNDS. 


Work,  Energy  and  the  Mechanical  Equivalent  of  Heat.  35 


Question  74.  How  many  foot-pounds  of  work  are  performed  in  a pile- 
driving  machine  in  raising  a weight  of  igoo  lbs.  24  feet  ? 

Answer.  1,200x24=28,800  foot-pounds. 

QUESTION  75.  When  this  weight  is  raised , is  the  force  which  was 
exerted  in  raising  it  annihilated  or  lost  ? 

Answer.  No ; because  the  force  with  which  it  is  attracted  towards  the 
earth — which  has  been  overcome  in  raising  the  weight — gives  it  the 
capacity  of  doing  an  equal  amount  of  work  when  it  falls.  Now,  although 
the  weight  has  no  motion-producing  power  when  it  is  raised  to  the  top  of 
the  machine,  yet,  obviously,  such  action  is  then  possible  which,  when  it 
rested  on  the  earth,  was  not  possible.  If  the  weight  is  allowed  to  fall,  it 
acquires  a greater  velocity  the  farther  it  falls,  and  it  can  then  do  work,  as 
in  driving  piles.  This  capacity  for  doing  work  is  called  energy.  It  has 
no  energy  as  it  hangs  there  dead  and  motionless  ; but  energy  is  possible 
to  it,  and  we  might  fairly  use  the  term  possible  energy  to  express  this  power 
of  motion  which  the  weight  possesses*  after  it  is  raised  up,  and  which 
is  therefore  called  potential  energy.  As  soon  as  the  weight  is  allowed 
to  fall  and  acquires  velocity  its  potential  energy  then  becomes,  and  is 
called,  actual  energy. 

Question  76.  How  can  such  phenomena  as  the  heating  of  a car-axle 
while  turning  under  a car,  the  heating  of  brake-blocks  when  the  brakes  are 
applied  to  car-wheels,  the  heating  of  an  iron  rod  by  hammering,  and  of  a 
turning  tool  when  cutting  a piece  of  metal  be  explained? 

Answer.  All  of  these  phenomena  are  due  to  the  fact  that  the  actual 
energy  of  motion  is  converted  into  heat,  as  has  been  repeatedly  proved  by 
many  able  and  ingenious  investigators  and  experiments. 

Question  77.  When  the  weight  of  the  pile-driver  falls,  is  its  energy 
also  converted  into  heat  ? 

Answer.  A part  is  expended  in  compressing  the  material  into  which 
the  pile  is  driven,  and  in  overcoming  the  friction  of  the  earth  against  the 
pile,  each  of  which  efforts  develops  heat,  and  another  portion  is  converted 
into  heat  by  the  impact  or  blow  of  the  falling  weight  on  the  head  of  the  pile. 

QUESTION  78.  Is  all  energy  convertible  into  heat  and  heat  into  energy? 

Answer.  Yes.  Science  has  demonstrated  very  clearly  that  they  are 
mutually  convertible. 

Question  79.  Has  it  been  ascertained  how  much  heat  is  equivalent  to 
one  foot-pound  of  work  ? 

Answer.  Yes.  It  has  been  found  from  carefully-made  experiments  that 


♦Tyndall’s  “ Heat  Considered  as  a Mode  of  Motion.” 


36 


Catechism  of  the  Locomotive. 


the  amount  of  heat  which  is  required  to  raise  the  temperature  of  one 
pound  of  liquid  water  by  one  degree  of  Fahrenheit*  is  equivalent  to  772 
foot-pounds  of  work.f  It  must  be  remembered  that  this  is  the  theoretical 
equivalent  of  heat,  and  that  only  a very  small  proportion  of  this  amount 
of  work  is  ever  realized  from  the  heat  developed  by  the  combustion  of 
fuel. 

Question  80.  If,  then,  heat  is  convertible  into  work  and  work  into  heat, 
can  the  transmutation  of  the  heat  of  the  steam  in  the  cylinder  of  an  engine 
into  work  and  the  reverse  process  be  explained  ? 

Answer.  Take  a'dylinder,  fig.  25,  and,  in  order  to  make  the  conditions 
of  the  experiment  Js  simple  as  possible,  imagine  it  to  be  placed  in  a 

l 


O 


Fig  25.  Cylinder  and  Piston.  Scale  % in.=l  foot. 

vacuum.  Now  let  saturated  steam  be  admitted  under  the  piston,  B,  so  as  to 
fill  the  cylinder  half  full  at  an  absolute  pressure  of  100  lbs.  If  we  will  allow 
this  steam  to  expand  to  double  its  volume  and  raise  the  piston  without 
doing  any  work,  and  then  repeat  the  experiment  with  a load  of  50  lbs.  on 
the  piston,  whose  area  is  one  square  inch,  it  will  be  found  that  the  tempera- 
ture of  the  steam  is  sensibly  less,  after  lifting  the  weight,  than  in  the  pre- 
vious experiment,  in  which  it  expanded  without  doing  work,  showing  that 
part  of  the  heat  was  abstracted  from  the  steam  by  doing  work,  or,  in  other 
words,  was  converted  into  work.  If  then,  after  the  steam  has  expanded 
and  lifted  the  weight,  we  press  the  piston  down  so  that  the  steam  under 

* Thermometers  are  divided  into  different  scales.  The  one  called  the  Fahrenheit  scale,  after 
its  originator,  is  the  one  ordinarily  used  in  this  country. 

t More  recent  experiments,  made  by  Prof.  Rowland  in  Baltimore,  show  that  the  mechanical 
equivalent  of  heat  is  778  foot-pounds  of  work. 


Work,  Energy  and  the  Mechanical  Equivalent  of  Heat.  37 


the  piston  is  compressed  to  its  original  volume,  we  shall  find  that  its  tem- 


perature is  the  same  as  before,  as  the  work  done  in  compressing  it  is  con- 
verted into  heat.  In  these  experiments  it  is  assumed  that  there  is  no 
friction  of  the  piston,  nor  loss  of  heat  from  radiation  or  conduction.  The 
same  phenomena  can  be  observed  in  machines  used  for  compressing  air. 
In  these,  the  air  is  heated  to  so  high  a temperature,  1 
that  it  is  sometimes  necessary  to  cool  the  cylinders  t 
of  cold  water  around  them. 

Question  81.  What  practical  relation  is  there  bt 
of  heat  mto  work  and  the  cojiducting  and  radiating 
substances  explained  in  answer  to  Q,uestio?i  Ji  ? 

Answer.  The  fact  that  heat  is  only  another  fori 


power  of  doing  work,”  indicates  that  its  loss  by  conduXiotf  or  radiation 
lessens  that  power  just  as  much  as  or  more  than  the  loss  or  waste  of  coal 
would,  and  therefore  every  effort  should  be  made  to  protect  the  different 
parts  of  engines  from  loss  of  heat  by  covering  them  with  substances  which 
conduct  or  radiate  very  little  heat.  Care  should  also  be  taken  to  exclude 
cold  air  from  circulating  in  contact  with  those  parts,  and,  excepting  for 
supporting  combustion,  the  nature  of  which  will  be  explained  hereafter,  it 
should  be  excluded  from  the  heating  surface  of  boilers. 

Question  82.  What  is  7neant  by  the  term  latent  heat  of  evapora- 
tion ? 

Answer.  By  latent  heat  is  meant  that  heat  which  apparently  disappears 
when  water  or  other  liquids  are  vaporized.  Thus,  it  is  found  that  if  any 
quantity  of  water  is  converted  into  steam  at  any  pressure,  it  is  necessary 
not  only  to  heat  the  water  to  a temperature  equivalent  to  that  of  the  steam, 
or  to  the  boiling-point,  but  after  the  water  has  reached  that  temperature 
an  additional  amount  of  heat  must  be  added  in  order  to  keep  up  the  pro- 
cess of  boiling.  Notwithstanding  this  addition  of  heat  to  the  water,  the 
temperature  of  the  steam  produced  will  not  be  higher  than  that  of  the 
boiling  water,  thus  showing  that  a considerable  quantity  of  heat  is  ab- 
sorbed, the  effect  of  which  is  to  change  the  water  into  a gas  or  steam. 
This  apparent  disappearance  of  heat  can  be  shown  if  we  take  a pound  of 
boiling  water  whose  temperature  is  212  degrees  and  mix  it  with  a pound 
of  ice-cold  water  at  32  degrees  temperature.  The  result  will  be  a mixture 
of  two  pounds  of  water  of  a mean  temperature  of  122  degrees.  If  now  we 
convert  a pound  of  water  into  steam  at  atmospheric  pressure,  its  tempera- 
ture will  also  be  212  degrees,  but  it  will  heat  6.37  lbs.  of  ice-cold  water  up 
to  122  degrees,  showing  that  a pound  of  steam  at  atmospheric  pressure 


38 


Catechism  of  the  Locomotive. 


contains  over  six  times  as  much  heat  as  a pound  of  water  of  the  same 
temperature  as  indicated  by  a thermometer.  A similar  apparent  disap- 
pearance of  heat  occurs  when  other  liquids  are  evaporated,  and  when  ice 
or  any  other  solid  is  converted  into  a liquid. 

Question  83.  What  is  the  explanation  of  these  phenomena? 

Answer.  The  exact  reasons  which  will  explain  them  fully  are  probably 
not  yet  clearly  understood,  but  it  is  at  least  extremely  probable  that  when 
any  substance  is  changed  from  a solid  to  a liquid,  “a  large  portion  of  the 
heat  is  spent  in  doing  work  against  the  force  of  cohesion.”*  The  particles 
of  solid  bodies,  as  w£  know,  are  so  united  that  it  requires  more  or  less 
force,  according  toithe  nature  of  the  substance,  to  tear  them  apart. 
Now,  we  can  conceive  that  when  the  heat  is  applied  to  some  solid 
substances,  such  as  ice  and  metals,-  that  it  is  changed  into  a form  of 
energy,  and  in  that  condition  resists  this  attraction  of  the  particles  to 
each  other  and  they  then  melt.  Further  application  of  heat  imparts 
more  energy  to  the  substances  and  they  then  assume  a gaseous  form, 
and  their  particles  repel  each  other.  When  the  heat  is  thus  trans- 
formed it  has  lost  the  capacity  of  expanding  the  mercury  in  the  ther- 
mometer. In  a liquid  condition  the  particles  of  the  substance  move  freely 
about  each  other  and  have  little  or  no  attraction  for  each  other,  but  when 
it  becomes  a gas  they  have  a repulsion  from  each  other.  The  heat  is  thus 
converted  into  the  energy  of  repulsion,  and  therefore  is  in  reality  no  longer 
in  the  condition  of  heat  and  consequently  does  not  affect  the  thermometer. 
We  can  illustrate  this  by  supposing  that,  by  using  steam,  heat  is  converted 
into  work  by  raising  the  weight,  or  drop  as  it  is  called,  of  a pile-driving 
machine.  When  the  weight  is  raised  to  the  top  of  the  guides  from  which 
it  falls,  although,  as  already  explained,  the  heat  is  converted  into  potential 
ejiergy , yet  if  we  attached  a thermometer  to  the  drop  we  would  not  find 
that  it  was  any  warmer  than  before  the  drop  was  raised.  If  it  were  possi- 
ble to  make  an  instrument  sufficiently  sensitive  to  indicate  an  instantane- 
ous change  of  temperature  in  the  weight  while  falling,  we  would  not  find 
any  increase  of  its  temperature  at  the  instant  it  had  acquired  its  greatest 
momentum  and  just  before  it  struck  the  object  under  it,  although  its 
potential  energy  would  at  that  instant  be  converted  into  actual  energy  of 
motion.  If,  however,  the  weight  should  strike  an  unyielding  object',  its 
actual  energy  would  at  once  be  reconverted  into  heat,  which  our  ther- 
mometer would  indicate.  The  phenomenon  of  what  is  called  latent  heat 
of  evaporation,  or  “ heat  of  gasification,”  seems  to  be  very  similar  to  that 

* Balfour  Stewart  on  the  Conservation  of  Energy. 


Work,  Energy  and  the  Mechanical  Equivalent  of  Heat.  39 

described — the  heat  when  the  water  is  changed  from  a liquid  to  a gaseous 
condition  is  transformed  into  energy,  which,  as  already  stated,  has  no 
effect  upon  the  mercury  of  the  thermometer. 

Question  84.  What  is  meant  by  the  total  heat  of  steam? 

Answer . The  “ total  heat  of  steam  ” is  a phrase  used  to  denote  the  sum 
of  the  heat  required  to  raise  the  temperature  of  water  from  some  given 
point  up  to  the  boiling-point  due  to  a given  pressure,  and  of  the  heat 
which  disappears  in  evaporating  one  pound  of  water  under  a given  pressure 
(or  latent  heat  of  eruafioratiori).  Thus,  the  latent  heat  of  one  pound  of 
steam  at  atmospheric  pressure  (14.7  lbs.)  is  966.1  units ; and  212  units  of 
heat  are  necessary  to  raise  water  from  zero  to  the  boiling-point ; therefore, 
the  total  heat  counted  from  zero  of  steam  of  atmospheric  pressure  is 
1,178.1  units.*  At  100  lbs.  absolute  pressure  the  latent  heat  is  885.5 
and  the  sensible  heat  327.9  degrees;  therefore  the  total  heat  mea- 
sured from  zero  is  1,213.4  units.  The  table,  in  Appendix  I,  gives  the  tem- 
perature, total  heat  in  degrees  from  zero  of  Fahrenheit’s  thermometer, 
weight  of  a cubic-foot,  and  the  volume  of  steam  of  pressure  from  1 to  300 
lbs.  per  square  Inch. 


* The  total  heat  is  sometimes  measured  from  the  freezing-point,  32  degrees. 


CHAPTER  VI. 


THE  STEAM  ENGINE. 

QUESTION  85.  What  is  the  motive  power  employed  in  ordinary  steam 
engines  ? 

Answer.  The  expansive  force  of  steam. 

Question  86.  How  is  this  expansive  force  of  steam  applied? 

Answer.  It  is  applied  by  admitting  it  into  a cylinder,  A,  fig.  26,  in  which 


cgd 


Fig.  26.  Cylinder  and  Piston.  Scale  % in.=l  ft. 

a piston,  B,  is  fitted  so  as  to  move  air-tight  from  one  end  of  the  cylinder 
to  the  other.  The  steam,  if  admitted  at  c,  will  force  the  piston,  B,  to  the 
opposite  end*  of  the  cylinder.  When  it  has  reached  that  end,  if  the  steam 
is  allowed  to  escape,  and  a fresh  supply  is  admitted  to  the  other  end  of 
the  cylinder  through  the  opening,  d,  it  will  move  the  piston  back  again. 
In  this  way,  by  alternately  admitting  steam  at  one  end  and  exhausting  it 
from  the  other,  the  piston  receives  a reciprocating  motion,  which  is  com- 
municated to  the  outside  of  the  cylinder  by  a rod,  R,  which  is  called  the 
piston-rod,  which  works  air-tight  through  an  opening  in  one  of  the  cylinder- 
covers,  or  cylinder-heads,  as  they  are  usually  called. 

Question  87.  How  is  this  reciprocating  motion  of  the  piston  converted 
into  rotary  motion  ? 

Answer.  By  connecting  the  end  of  the  piston-rod,  R,  fig.  A,  Plate  I 
(ia  the  back  part  of  the  book),  by  another  rod,  E (called  a connecting-roa), 
with  a crank,  P,  which  is  attached  to  a revolving  shaft,  S.  It  is  apparent 

* In  all  ordinary  locomotives,  the  cylinders  are  so  placed  that  the  head,  X , through  which  the 
piston-rod  works,  is  behind,  and  the  other  head,  W , in  front.  The  two  ends  of  the  cylinder  are 
therefore  designated  the  front  and  back  ends , respectively. 


The  Steam  Engine. 


41 


that  if  the  piston,  B,  is  moved  in  the  direction  shown  by  the  dart,  R , a 
rotary  motion  will  be  given  to  the  crank  in  the  direction  of  the  dart,  n. 
When,  however,  the  crank  reaches  the  position  shown  by  the  dotted  lines 
at  N',  it  is  plain  that  a force  applied  to  move  the  piston  in  either  direction 
will  no  longer  produce  a rotary  movement  of  the  crank  and  shaft.  The 
same  thing  will  occur  when  the  crank  is  in  the  opposite  position.  These 
two  positions  are  called  the  dead-points  of  the  crank. 

Question  88.  How  is  the  crank  of  an  ordinary  steam  engine  carried 
past  the  dead-points  ? 

Answer.  A stationary  engine  usually  has  a large  and  heavy  wheel,  called 
a fly-wheel , F,  Plate  I,  which  is  attached  to  the  shaft,  S.  This  wheel 
receives  a sufficient  amount  of  momentum  from  the  crank,  while  the  latter 
is  moving  from  one  dead-point  to  the  other,  to  carry  it  past  those  points. 

Question  89.  How  is  the  steam  admitted  to  and  exhausted  from  the 
cylinder  ? 

Answer.  It  is  admitted  through  two  channels,  cc'  and  dd" , called  steam- 
passages , cast  in  the  cylinder.  These  passages  terminate  in  a smooth,  flat 
surface,  ff,  called  the  valve-seat.  The  openings,  c and  d , fig.  C,  Plate  I.,  of 
the  steam-ports  in  the  valve-seat,  are  called  steam-ports.  Between  them  is 
another  port  or  cavity,  g,  called  the  exhaust-port , which  communicates 
with  the  open  air.  The  form  of  these  ports  is  long  and  narrow,  as  shown 
in  fig.  C,  which  represents  a plan  of  the  engine,  or  a view  looking  down 
from  above  it,  with  the  top  of  the  steam-chest  and  valve  removed.  Over 
these  ports  a valve,  V,  figs.  A and  B,  called  a slide-valve , which  is  usually 
made  of  cast-iron,  with  a cavity,  H,  in  its  under  side — is  fitted  so  that  by 
moving  it  backward  or  forward  it  will  alternately  cover  and  uncover  the 
two  steam-ports.  The  valve  and  valve-seat  are  inclosed  in  a sort  of  box, 
II,  made  of  cast-iron,  called  a steam-chest,  into  which  steam  is  admitted 
from  the  boiler  by  a pipe,  f.  When  the  valve  is  in  the  position  repre- 
sented in  fig.  A,  the  front  steam-port,  c,  is  uncovered,  and  the  steam  is 
admitted  to  the  front  end  of  the  cylinder,  as  indicated  by  the  darts  c and 
c',  and  it  thus  forces  the  piston  toward  the  back  end,  or  in  the  direction 
of  the  dart,  R.  If,  when  the  piston  reaches  the  back  end,  as  shown  in 
fig.  B,  the  valve  has  been  moved  into  the  position  shown,  the  back  steam- 
port,  d,  will  be  uncovered,  and  steam  will  be  admitted  to  the  back  end  of 
the  cylinder,  as  indicated  by  the  darts  d and  d' . At  the  same  time  it  will 
be  observed  that  the  front  steam-port,  c,  and  the  exhaust-port,  are  both 
covered  by  the  cavity,  H,  in  the  slide-valve,  so  that  the  steam  which  was 
admitted  to  the  front  end  of  the  cylinder  can  now  escape  as  indicated  by 


42 


Catechism  of  the  Locomotive. 


the  arrows,  c ' c,  through  the  steam-port  into  the  exhaust-port,  g,  and  thus 
into  the  open  air.  By  moving  the  valve  alternately  back  and  forth,  steam 
is  simultaneously  admitted  first  to  one  end  of  the  cylinder,  and  exhausted 
from  the  other,  and  vice  versa. 

Question  90.  How  is  the  slide-valve  moved  so  as  to  admit  and  exhaust 
the  stea7n  at  the  right  time  ? 

Answer.  This  is  done  by  means  of  what  is  called  an  eccentric,  G (shown 


Fig.  27.  Eccentric.  Scale  % in.— 1 ft. 


Fig.  28.  r 


l 


separately  in  figs.  27  and  28),  which  is  a circular  disc  or  wheel,  whose 
centre,  n,  is  some  distance  from  that  of  the  shaft,  S,  to  which  it  is  fastened 
with  keys  or  screws,  and  with  which  it  revolves.  The  outside  of  the 
eccentric  is  embraced  by  a metal  ring,  K K,  called  an  eccentric-strap , 
shown  in  fig.  29,  and  also  in  fig.  A of  Plate  I.  This  strap  is  made  in  two 
halves,  which  separate  in  the  line,  / /,  fig.  29.  The  two  parts  are  fastened 
together  by  bolts,  m m , which  pass  through  lugs  or  projections  cast  on  the 
straps,  as  shown.  The  outside,  or  the  periphery,  of  the  eccentric,  is  accu- 
rately turned,  and  the  inside  of  the  strap  is  bored  to  fit  it,  so  that  the  one 
can  revolve  inside  of  the  other. 

Question  91.  How  does  an  eccentric  work? 

Answer.  Its  action  is  precisely  like  that  of  a crank,  in  fact  it  may  be 


The  Steam  Engine. 


43 


defined  to  be  a crank  with  a crank-pin  large  enough  to  embrace  the  shaft. 

QUESTION  92.  How  is  the  motion  of  the  eccentric  imparted  to  the  valve  f 

Answer.  A rod,  Z,  called  an  eccentric-rod,  is  attached  to  the  eccentric- 
straps,  as  shown  in  fig.  29.  It  is  obvious  that,  if  the  eccentric  revolves 
inside  of  the  strap,  it  will  impart  a reciprocating  motion  to  the  rod,  Z. 
The  eccentric,  G,  strap,  K,  and  rod,  Z,  are  represented  in  fig.  A , Plate  I. 
Before  describing  their  operation,  or  rather  their  connection  with  the 
valve,  V,  it  is  necessary  to  understand  that  in  this  country  the  slide-valves 
of  locomotives  are  usually  placed  on  top  of  the  cylinders,  in  which  position 
it  is  difficult  to  connect  the  eccentric-rod  directly  with  the  valve.  For 
convenience,  therefore,  what  is  called  a rocker,  R R' , is  placed  between  the 
cylinder  and  the  main  shaft  of  the  engine. . This  rocker  has  two  arms 
attached  to  a shaft,  s,  and  the  two  arms  have  a vibratory  motion  about  it, 
as  indicated  by  the  dotted  lines,  r R and  R'  r' . The  eccentric-rod,  L,  is 
attached  by  a pin,  R',  to  the  lower  arm  of  the  rocker,  and  the  slide-valve, 
V,  is  connected  by  the  rod,  C,  called  the  valve-rod,  or  valve-stem,  to  a pin, 
R,  on  the  upper  end  of  the  rocker.  It  is  obvious  that,  as  the  eccentric,  G, 
revolves,  a reciprocating  or  vibratory  motion  will  be  given  to  the  rocker, 
which  will  be  communicated  to  the  valve  by  the  valve-stem  ; and  it  is  only 
necessary  to  fix  the  eccentric  in  the  proper  position  on  the  shaft,  in  rela- 
tion to  the  crank  and  piston,  to  give  the  valve  the  required  motion  for  ad- 
mitting and  exhausting  the  steam  to  and  from  the  cylinder  at  the  right  time. 

Question  93.  How  can  the  action  of  the  eccentric  and  the  movement  of 
the  valve  and  piston  during  a complete  revolution  of  the  crank  be  shown  ? 

Answer.  It  can  be  illustrated  and  explained  by  the  aid  of  a series  of 
diagrams — figs.  80-43.  In  these  diagrams  most  of  the  parts  are  repre- 
sented by  their  centre-lines  and  centre  points  only,  so  as  to  make  them  as 
simple  as  possible.  The  dimensions  selected  for  these  illustrations  are,  for 
the  cylinder,  16  inches  diameter  and  24  inches  stroke.  The  steam-ports  are 
1^  inches,  the  exhaust-port,  2£  inches,  and  the  metal  or  bars  between 
them,  which  are  called  bridges,  are  1£  inches  wide.  The  eccentric  pro- 
duces a lateral  movement  of  4 inches,  which  is  called  its  throw  * In  fig. 
30,  the  piston  is  at  the  beginning  of  the  backward  stroke. 

* There  is  some  ambiguity  in  the  use  of  the  term  throw.  In  Webster’s  dictionary  it  is  defined 
as  “the  extreme  movement  of  a slide-valve,  also  of  a crank  or  eccentric,  measured  on  a straight 
line  passing  through  the  centre  of  motion.”  The  definition  of  mechanical  terms,  in  the  edition 
of  the  dictionary  quoted  from,  were  prepared  by  the  late  Alexander  L.  Holley,  so  that  no  more 
eminent  authority  could  be  quoted  for  the  usuage  of  the  term  with  this  meaning.  Nevertheless, 
the  word  throw  is  sometimes  used  to  designate  the  distance  from  the  centre  of  a shaft  to  the 
centre  of  a crank-pin  or  eccentric,  which,  of  course,  would  be  only  one-half  the  extreme  move- 
ment of  a valve  or  piston. 


Diagrams  of  Engine.  Scale  % in.=?.  ft. 


Catechism  of  the  Locomotive. 


46 


It  will  be  seen  that  the  valve,  V,  has  then  uncovered  the  first  steam-port 
at  c,  and  that  steam  can  therefore  enter  the  front  end  of  the  cylinder  as 
indicated  by  the  darts.  At  the  same  time,  the  exhaust-cavity,  V,  in  the 
valve  covers  the  exhaust-port,  g , and  the  front  steam-port,  d,  so  that  the 
steam  in  the  back  end  of  the  cylinder  can  escape  as  shown  by  the  arrows. 

In  fig.  31,  the  piston  is  represented  as  having  moved  4 inches  of  its 
stroke  ; the  valve  has  then  opened  both  of  the  steam-ports  wider.  In  fig. 

32,  the  piston  has  moved  8 inches  of  its  stroke,  and  the  ports  are  now  wide 
open,  the  front  one  to  the  steam  and  the  back  one  to  the  exhaust.  In  fig. 

33,  the  piston  has  moved  12  inches,  or  is  at  half-stroke,  and  the  valve  has 
then  moved  to  its  extreme  throw.  In  fig.  34,  the  piston  has  moved  16 
inches,  and  the  valve  has  begun  to  return.  In  fig.  35,  the  piston  has  moved 
20  inches,  and  the  valve  has  nearly  closed  the  front  port  to  the  steam.  In 
fig.  36,  the  forward  stroke  is  completed,  and  the  back  steam-port  is  then 
slightly  opened  to  admit  steam  into  the  back  end  of  the  cylinder  for  the 
return  stroke.  The  front  steam-port  has  also  been  made  to  communicate 
with  the  exhaust-port  so  that  the  steam  in  the  front  end  of  the  cylinder 
will  be  exhausted  before  the  piston  begins  to  return. 

Figs.  37  to  43*  represent  the  positions  of  the  piston  and  valve  during 
the  forward  stroke,  corresponding  with  those  described  for  the  backward 
stroke.  The  darts  in  the  steam-ports  in  the  figures  represent  the  move- 
ment of  the  steam  in  each  position  of  the  piston  and  crank.  Other  darts, 
on  the  piston  and  at  the  crank-pin,  show  the  direction  in  which  they  are 
moving.  By  following  the  successive  positions  of  the  piston,  crank  and 
valve,  as  shown  in  these  figures,  the  reader  can  get  a very  clear  idea  of  the 
action  of  an  engine  of  the  kind  illustrated. 

Question  94.  How  is  the  piston  of  a steam  engine  made  to  work  steam- 
tight  in  the  cylinder  ? 

Answer.  The  cylinder  is  first  accurately  bored  out,  and  the  piston  has 
two  metal  rings  around  its  periphery.  Each  of  these  rings  is  cut  apart, 
as  shown  at  B,  in  fig.  A,  Plate  I,  so  that  they  can  be  expanded  by  springs 
or  other  means  to  fit  the  cylinder.  The  open  places  are  placed  at  different 
points  on  the  circumference  of  the  piston,  so  that  the  one  opening  is 
covered  by  the  other  ring,  which  prevents  the  steam  from  leaking  through  the 
openings.  The  construction  of  pistons  is  fully  described  in  Chapter  XV. 

Question  95.  How  is  the  piston-rod  made  to  work  steam-tight  through 
the  cylinder-head  ? 

* These  are  arranged  in  the  reverse  order  to  those  on  page  44  to  represent  the  forward  stroke 
of  the  piston. 


The  Steam  Engine. 


47 


Answer.  By  what  is  called  a stuffing-box . This  consists  of  a cylindrical 
chamber,  A A',  figs.  44  and  45,  the  inside  of  which  is  made  about  1-^  inches 


Stuffing-Box.  Scale  1^  in.=l  ft. 

larger  in  diameter  than  the  piston-rod.  This  leaves  an  annular  space  f of 
an  inch  wide  all  around  the  rod.  This  space  is  filled  with  hemp,  H,  or 
some  other  fibrous  material,  called  packing , saturated  with  oil  or  melted 
tallow.  This  packing  is  compressed  by  a hollow  cylinder,  C C' , called  a 
gland,  the  inside  of  which  fits  the  piston-rod,  P,  and  the  outside  the  stuff- 
ing-box. This  gland  is  forced  into  the  stuffing-box  by  nuts,  1 1' , which  are 
screwed  down  on  a flange,  u u' , attached  to  the  gland.  The  packing  is 
thus  compressed  in  the  stuffing-box  and  forced  against  the  piston-rod, 
which  is  made  smooth  and  perfectly  round  and  straight,  and  against  the 
side  of  the  stuffing-box,  so  that  no  steam  can  escape  around  the  piston- 
rod.  A brass  ring  or  “bushing,”  B,  is  often  put  into  the  gland,  and 
another  in  the  cylinder-head,  where  it  touches  the  piston-rod,  because 
brass  will  bear  the  friction  of  the  rod  better  than  cast-iron,  and,  when  it  is 
worn  out,  it  can  be  removed,  and  a new  one  substituted  in  its  place. 
Packing  made  of  metal  is  now  often  used  for  piston-rods  instead  of  fibrous 
material.  The  construction  of  metal  packing  is  described  in  Chapter  XV. 

Question  96.  How  must  the  piston  and  piston-rod  move  in  order  to 
keep  steam-tight  ? 

Answer.  The  centre  line  of  the  piston  and  piston-rod  must  always  be 
coincident  with  the  axis  or  centre  line  of  the  cylinder. 

QUESTION  97.  How  is  the  movement  of  the  piston-rod  affected  by  the 
connecting-rod  ? 

Answer.  Excepting  when  the  crank  is  at  one  of  the  dead-points,  the 


48 


Catechism  of  the  Locomotive. 


centre  line  of  the  connecting-rod  is  inclined  to  that  of  the  piston-rod  and 
axis  of  cylinder.  Consequently,  at  all  other  points  of  the  revolution,  the 
connecting-rod  has  a tendency  to  either  pull  or  push  the  end  of  the  piston- 
rod  downward,  when  the  crank  is  turning  in  one  direction,  or  upward  if 
the  crank  turns  the  opposite  way. 

Question  98.  How  is  this  action  of  the  connecting-rod  resisted? 

Answer.  The  back  end  of  the  piston-rod  and  the  front,  or  small  end , as 
it  is  called,  of  the  connecting-rod  are  attached  to  what  is  called  a cross- 
head, D,  shown  in  figs.  A and  B,  Plate  I.  This  moves  between  bars,  0 0, 
O'  O',  called  guide-bars,  which  are  set  so  that  the  motion  of  the  cross-head 
is  coincident  with,  or  parallel  to,  the  axis  or  centre  line  of  the  cylinder. 
As  the  end  of  the  piston-rod  is  attached  to  the  cross-head,  they  must  both 
move  in  a path  parallel  to  the  faces  of  the  guide-bars  on  which  the  cross- 
head slides.  In  this  way,  the  pressure  exerted  by  the  connecting-rod 
bears  on  the  guide-bars  and  is  resisted  by  them. 

Question  99.  How  is  the  connecting-rod  attached  to  the  crank-pin? 


Fig.  47.  Stub-End.  Scale  1J4  in.=l  ft. 


Answer.  By  what  is  called  a stub-end  or  strap-head,  shown  in  fig.  46, 
which  shows  a section  through  the  crank-pin,  P,  and  fig.  47,  which  is  apian 
or  view  looking  down  from  above.  A stub-end  consists  of  two  brass 
“ journal-bearings,”  or  “ brasses,”  A’  and  b,  which  embrace  the  crank-pin 


The  Steam  Engine. 


49 


and  bear  against  it.  These  bearings  are  attached  to  the  rod  by  the  strap, 
or  id  -shaped  bar,  S S'.  The  strap  is  fastened  to  the  end  of  the  connecting- 
rod,  R,  by  the  bolts, B B,  and  also  by  a key,  K ’,  and  “gib  ” or  “cotter,”  GG’ . 
A little  space,  or  “ clearance,”  c c',  is  allowed  between  the  gib,  G,  and  the 
strap,  S S',  and  also  between  the  key,  K,  and  rod,  R.  When  the  journal- 
bearings,  A b,  wear  by  reason  of  their  friction  on  the  crank-pin,  they  are 
taken  out  and  filed  away  at  f g,  on  their  surfaces  of  contact  with  each 
other.  The  key,  K , is  then  driven  down,  which  moves  the  strap  in  the 
direction  of  dart,  S — the  clearance,  at  c c’ , permitting  such  movement — 
which  draws  the  journal-bearings  together  and  takes  up  the  “ lost  motion,” 
as  the  wear  of  the  journals  is  called. 

Question  100.  Why  are  the  journal-bearings  made  of  brass? 

Answer.  Because  brass  resists  the  wear  of  a journal,  when  the  pressure 
on  it  is  very  great,  better  than  iron  or  steel.  That  is,  brass  bearings  are 
less  liable  to  get  hot  or  be  abraded  than  either  iron  or  steel. 

Question  101.  Are  the  engines — that  is,  the  cylinders  and  other  mechan- 
ism— which  are . used  in  locomotives , similar  in  principle  and  construction  to 
the  stationary  engines  that  have  been  described  ? 

Answer.  Yes  ; the  chief  difference  is  that  in  locomotives  two  cylinders 
and  cranks  are  used  so  as  to  overcome  the  difficulty  there  would  be  in 
starting  from  the  dead-points  if  only  one  was  used,  and  the  valve  gear  is 
also  arranged  so  that  the  motion  of  the  engine  can  easily  be  reversed. 


CHAPTER  VII. 


THE  EXPANSIVE  ACTION  OF  STEAM. 

Question  102.  How  is  the  expansive  action  of  steam,  referred  to  in  the 
answer  to  question  62,  utilized  in  a steam  engine  ? 

Answer.  The  valve  and  its  movement  are  so  arranged  that  tne  steam- 
ports,  through  which  steam  is  admitted  to  the  cylinder,  are  each  open 
during  a portion  only  of  the  stroke  of  the  piston.  When  the  piston  has 
moved  through  a part  of  its  stroke,  the  port  through  which  steam  is  enter- 
ing the  cylinder  is  closed,  without  allowing  the  steam  which  has  been 


admitted  to  the  cylinder  to  escape,  until  the  piston  has  nearly  reached  the 
end  of  its  stroke.  Consequently,  when  the  steam  is  thus  enclosed,  or 


The  Expansive  Action  of  Steam. 


51 


“cut-off”*  as  it  is  termed,  its  expansive  action  continues  to  exert  a dimin- 
ishing pressure  against  the  piston  until  the  exhaust-port  is  opened.  Thus, 
in  fig.  35,  it  will  be  seen  that  the  valve  has  nearly  closed  the  steam-port, 
although  the  piston  has  not  yet  reached  the  end  of  its  stroke.  Fig.  48 
shows  the  valve  on  an  enlarged  scale  in  the  position  it  occupies  when  the 
steam-port,  c,  is  first  closed  ; and  in  fig.  49  the  valve  is  represented  after  it 
has  moved  far  enough  to  begin  to  open  communication  from  the  steam- 
port,  c,  to  the  exhaust-port,  g,  as  indicated  by  the  dart,  d.  While  the  valve 
is  moving  from  the  position  in  which  it  is  shown  in  fig.  48  to  that  repre- 
sented in  fig.  49,  it  is  evident  that  the  steam-port,  c,  will  be  covered  by  the 
valve,  and  therefore  during  that  period  the  steam  is  confined  in  the  front 
end  of  the  cylinder  and  expands  as  the  piston  advances.  It  thus  exerts  a 
pressure  on  the  piston  after  the  steam-port  is  closed.  As  the  piston  advan- 
ces, and  the  space  or  volume  occupied  by  the  steam  in  the  cylinder  is 
increased,  the  pressure  of  the  steam  is  reduced  as  was  explained  in  answer 
to  question  64. 

Question  103.  How  can  we  know  how  much  pressure  is  exerted  by  the 
steam  during  expansion  ? 

Answer.  As  explained  in  answer  to  question  64,  the  pressure  of  air  or 
steam  is  inversely  proportional  to  its  volume.  This  can  be  shown  if  we 
have  a cylinder,  A,  which  is  shown  in  section  in  fig.  50,  with  a piston,  P, 
fitted  so  as  to  work  air-tight  in  the  cylinder.  If  the  space  in  front  f of  the 
piston  is  filled  with  air  of  15  lbs.  absolute  pressure  per  square  inch,  which 
is  equal  to  the  ordinary  atmospheric  pressure.  Let  it  be  supposed  that  a 
tube,  T,  is  screwed  into  the  cylinder  just  in  front  of  the  piston,  P,  and  that 
this  tube  also  has  a small  piston,  P,  whose  area  is  just  one  square  inch, 
fitted  in  it,  so  as  to  work  air-tight  from  one  end  to  the  other,  and  that  a 
spiral  spring,  s,  inside  of  the  tube,  bears  on  top  of  the  piston,/.  The  ten- 
sion of  this  spring  is  such  that  for  every  10  lbs.  of  pressure  exerted  below 
the  piston  it  will  be  moved  upward  a distance  equal  to  the  spaces  between 
the  horizontal  lines  drawn  behind  the  tube. 

The  spring  is  also  proportioned  so  that  if  there  was  no  pressure  or  a 
vacuum  below  the  piston,  P,  the  air  above  it  would  extend  the  spring  and 
force  the  piston  downward  so  that  it  would  then  rest  on  the  bottom  of 
the  tube,  but  as  there  is  supposed  to  be  atmospheric  pressure  both  above 


*The  steam  is  said  to  be  "'cut-off'"  when  the  steam-port  or  opening  by  which  steam  is 
admitted  to  the  cylinder  is  closed  by  the  valve. 

f The  piston-rods  cf  locomotives  almost  always  pass  through  the  back  cylinder-heads.  There- 
fore the  opposite  end  becomes  the  front  of  the  cylinder  and  it  will  be  so  designated  hereafter. 


'ABSOLUTE.  PRESSURE.  PER  SQ.  IN. 


52 


Catechism  of  the  Locomotive. 


3HERIC  | 


VACUUM  LINE 


Fig.  50.  Cylinder,  Piston  and  Diagrams,  to  show  the  effect  of  Compression  and  Expansion  of 
Air  and  the  Properties  of  Steam. 


The  Expansive  Action  of  Steam. 


53 


and  below  the  piston,  its  lower  side,  / , stands  at  a distance  equal  to 
1-J-  times  the  spaces  between  the  horizontal  lines  above  the  bottom 
of  the  tube.  If  there  was  a vacuum  below  the  piston  it  would  be  forced 
down  to  the  bottom  by  the  air  above  it,  therefore,  a horizontal  line,  o o, 
corresponding  with  that  position  is  called  the  “ Vacuum  Line,”  and  as  the 
piston  would  stand  at  a distance  of  1£,  the  spaces  between  the  lines 
above  o o,  when  there  is  atmospheric  pressure  both  above  and  below 
it,  a dotted  horizontal  line,  15  15,  is  drawn  through  this  position  and  is 
called  the  “Atmospheric  Line.”  As  explained  before,  the  horizontal  lines 
are  drawn  and  the  spring,  T,  is  so  proportioned  that  for  every  10  lbs.  of 
pressure  exerted  below  the  piston  it  is  pushed  up  a distance  equal  to  the 
spaces  between  the  lines.  Consequently  the  pressures  corresponding  to 
the  position  of  these  lines,  above  the  vacuum  line,  o o,  are  marked  on  the 
left-hand  side  of  the  engraving,  and  the  position  of  the  piston  in  relation 
to.  these  lines  will  thus  indicate  the  pressure  below  it.  Its  position,  at  p, 
shows  that  there  is  an  absolute  pressure  of  15  lbs.,  equal  to  atmospheric 
pressure,  under  it. 

If,  now,  we  should  push  the  piston-rod,  P,  forward  so  as  to  move  the 
piston,  P,  towards  the  front  end  of  the  cylinder,  the  air  enclosed  in  it  would 
be  compressed.  Let  it  be  supposed  that  it  is  moved  so  that  the  face,  a b, 
of  the  piston  corresponds  with  the  dotted  line,  12  12',  and  that  the  distance, 
e'  e' , of  the  face  from  the  front  head  is  only  half  of  e e.  The  air  in  front  of 
the  piston  would  then  be  compressed  into  half  the  space  it  occupied  before, 
and,  as  explained  in  answer  to  Question  64,  its  pressure  will  then  be  doubled. 
If,  now,  the  cylinder,  A,  had  another  tube,  7",  like  T,  located  above  the  line, 
12  12',  then  when  the  piston,  P,  reached  the  line,  12  12',  the  air  which  is 
compressed  in  the  front  end  of  the  cylinder,  A,  would  force  the  piston,/', 
upward,  in  T' , until  its  lower  side  corresponds  with  the  horizontal  line, 
marked  30,  thus  indicating  that  the  pressure,  in  A,  is  equal  to  30  lbs.  per 
square  inch.  If  the  piston,  P,  is  pushed  still  further  forward,  to  6 18',  so 
that  its  distance,  e"e",  from  the  front  end  of  the  cylinder,  is  only  half  of  e'e', 
the  pressure  of  the  air  will  again  be  doubled,  or  would  be  equal  to  60  lbs. 
per  square  inch,  as  would  be  indicated  by  the  piston,/",  in  the  tube,  T".  If 
the  piston,  P,  was  moved  to  3 21',  the  distance,  e"'  e'",  would  be  only 
i the  distance,  e e,  so  that  the  air  which  originally  had  a pressure  of 
15  lbs.  would  now  have  120  lbs.,  which  would  be  indicated  by  the  piston,/"'. 
The  positions  of  the  pistons,//'/"  and/'",  will  thus  show  the  pressure 
when  the  piston,  P,  is  in  the  positions  24  O',  12  12',  6 18'  and  3 21'. 

If  the  piston,  P,  was  pushed  still  nearer  to  the  front  end  of  the  cylinder 


54 


Catechism  of  the  Locomotive. 


so  that  e""  e""  was  equal  to  \ of  e"r  e'” , or  only  If  inches,  then  the  pres- 
sure of  the  air  would  again  be  doubled,  and  be  240  lbs.,  and  if  there 
was  another  tube  and  piston  similar  to  T" , but  of  sufficient  length,  its 
piston  would  be  forced  up  to  and  would  then  indicate  the  pressure 
after  the  air,  which  filled  the  whole  cylinder,  was  compressed  sixteen 
times. 

If  we  draw  a curve,  p""  p'"  p"  p'  p,  through  the  positions  of  the  pistons 
which  indicate  the  pressure,  then  the  distance  of  this  curve  above  the 
vacuum  line,  oo,  will  show  the  pressure  in  the  cylinder.  A,  during  the  whole 
period  while  the  piston,  P,  is  moving  from  24  O'  to  If  22f\  Thus,  when  it 
has  moved  from  O'  to  6',  or  6 inches  of  its  stroke,  the  pressure  is  then 
measured  by  the  vertical  distance,  18  g,  of  the  curve  above  the  vacuum 
line,  and  when  it  has  moved  from  0'  to  15',  or  15  inches,  the  pressure  is 
measured  by  g f. 

If,  on  the  other  hand,  air  of  a higher  pressure  is  allowed  to  expand  in  a 
cylinder  so  as  to  have  a lower  pressure,  just  the  reverse  action  takes  place. 
Thus,  if  the  piston,  P,  occupied  the  position,  3 21',  so  that  the  distance,  e'" 
of  its  face  was  3 inches  from  the  front  end  of  the  cylinder,  and  the  space, 
0 3 21'  24',  was  filled  with  air  of  120  lbs.  pressure,  and  it  was  then  allowed  to 
expand  and  push  the  piston  to  6 18',  so  that  the  space,  0 6 18'  24',  occupied, 
or  the  volume  of  the  air  was  double  what  it  was  before,  then  the  pres- 
sure would  be  f of  120,  or  60  lbs.  per  square  inch,  which  would  be  indi- 
cated by  the  piston,  p” . If  the  piston,  moved  to  12  12',  so  that  the 
volume  of  the  air  was  four  times  what  it  was  at  first,  its  pressure  would  be 
f of  120,  or  30  lbs.,  and  would  be  indicated  by  the  piston,  /',  or  if 
it  was  expanded  to  fill  the  whole  cylinder,  or  to  occupy  eight  times  its 
original  volume,  its  pressure  would  then  be  only  15  lbs.  If  a curve,/'" 
p"  p'  p,  is  drawn  through  the  successive  positions  of  the  pistons, 
p,  this  curve  will  represent  the  pressure  of  the  air  during  the  whole  move- 
ment of  the  piston.  Such  a curve  is  called  an  “ expansive  curve.” 

Question  104.  Do  all  gases  act  in  conformity  with  Boyle's  law  as  ex- 
plained in  answer  to  Question  64  ? 

Answer.  All  of  what  are  known  as  fixed  gases — that  is,  those  which 
cannot  be  readily  liquefied  by  cold  or  pressure — with  slight  variations,  act 
in  accordance  with  this  law,  but  steam  and  some  other  gases,  which  can 
be  condensed  easily,  vary  somewhat  from  it,  as  was  explained  in  answer 
to  Question  67.  Some  of  the  reasons  for  this  variation  are  not  yet  thor- 
oughly understood,  and  the  explanation  of  those  which  are  would  require 
the  use  of  mathematics,  and  the  explanation  of  abstruse  scientific  princi- 


The  Expansive  Action  of  Steam. 


55 


pies,  which  would  be  out  of  place  in  an  elementary  book  like  this.  For 
the  present  these  variations  may  be  disregarded,  as  all  that  is  now  aimed 
at  is  to  give  a general  idea  of  the  nature  of  the  law  which  governs  the 
volume  and  pressure  of  gases. 

In  calculating  the  pressure  of  steam  before  and  after  compression  or 
expansion,  it  must  always  be  kept  in  mind  that  the  absolute  pressure  must 
be  taken  in  making  the  calculations.  The  working  pressure  can  then  be 
ascertained  by  deducting  the  atmospheric  pressure,  or  15  lbs.  per  square 
inch,  from  the  results  of  the  calculations. 

Question  105.  How  may  an  expansive  curve  be  most  easily  drawn? 


Answer.  As  such  curves  nearly  always  represent  the  expansion  of  steam 
in  a cylinder,  a horizontal  line,  0 24,  fig.  51,  should  be  first  laid  down  to 


56 


Catechism  of  the  Locomotive. 


any  convenient  scale  to  represent  the  “stroke”*  of  the  piston,  and  this 
line  should  then  be  subdivided  into  any  convenient  number  of  divisions, 
and  vertical  lines  drawn  through  these  subdivisions.  The  line,  0 24,  may 
then  be  regarded  as  the  vacuum  line.  Supposing  now  that  it  is  desired  to 
lay  down  an  expansion  curve  for  steam  of  120  lbs.  absolute  pressure,  which 
fills  3 inches  in  length  of  the  cylinder,  shown  in  fig.  50.  On  the  left  hand 
vertical  line  of  fig.  51  lay  off  to  any  convenient  scale,  a distance,  0 120  above 
0 24,  representing  the  steam  pressure.  As  the  steam  fills  3 inches  of  the  cyl- 
inder, draw  a horizontal  line,  120/'",  equal  to  3 inches.  . The  rectangle,  120 
ft"'  3 0,  will  then  represent  the  volume  of  the  steam  before  expansion,  which 
is  supposed  to  begin  at  ft’" . By  the  rule  given  in  answer  to  Question  65, 
calculate  the  pressure  of  the  steam  from  any  degree  of  expansion,  say  to 
double  its  volume,  which  would  give  a pressure  of  60  lbs.  On  the  vertical 
line,  6 n — which  is  twice  as  far  from  o,  the  beginning  of  the  stroke,  as  3 ft'" 
is — lay  off,  6 ft" , equal  to  the  pressure,  60  lbs.,  after  expansion  has  taken 
place.  In  a similar  way  calculate  for  a four-fold  expansion,  and  lay  off 
on  12  n",  12  ft'=to  30,  and  for  eight-fold  lay  off  24  ft = to  15,  on  24  q. 
Now,  through  the  points  thus  laid  off,  draw  the  curve,  ft"’  ft"  ft'  ft,  which 
will  be  the  expansion-curve.  In  practice  it  is  well  to  calculate  the  pres- 
sure for  more  points  of  the  stroke  in  order  to  be  able  to  lay  down  the 
curve  accurately. 

Another  method  of  drawing  such  a curve  without  calculations  is  to  lay 
down  the  rectangle,  120  ft'"  3 0,  to  represent  the  volume  and  pressure  of 
the  steam.  Extend  the  line,  120/'",  parallel  to  0 24,  to  q.  To  find  the 
pressure  at  any  point  of  the  stroke,  6,  for  example,  corresponding  to  the 
volume,  0 6,  draw  the  vertical  6 n,  and  draw  a line,  o n,  through  0,  the 
extremity  of  0 24,  and  n the  intersection  of  6 n,  with  120  q.  Then  draw  a 
horizontal  line,  aft",  through  a,  the  intersection  of  o nvf  ixh  3 ft'",  and  the 
intersection  of  a ft"  with  the  vertical,  6 n,  will  then  represent  the  pressure 
at  6 inches  of  the  stroke  and  it  will  be  one  point  in  the  curve.  Any  num- 
ber of  other  points  may  be  obtained  in  the  same  way — as  d,  by  drawing  p 
n' , 0 n'  and  c d — and  the  curve  can  then  be  drawn  through  these  points.! 

Question  106.  How  can  the  relation  existing  between  the  heat,  ftressure 
and  volume  of  steam  be  shown  ? 

Answer.  The  table  which  is  published  in  Appendix  I,  gives  the  pres- 

* The  “ stroke  ” of  the  piston  is  the  distance  it  moves  in  the  cylinder,  and  in  ordinary  engines 
is  always  twice  the  length  of  the  crank,  measured  from  centre  to  centre  of  the  shaft  and  crank- 
pin. 

+ From  Steam,  by  William  Ripper. 


The  Expansive  Action  of  Steam.  57 

sure,  the  temperature,  the  total  heat,  the  weight  and  the  relative  volume 
of  steam  compared  with  the  water  from  which  it  was  raised,  and  a study 
of  this  table  will  give  an  idea  of  the  relation  referred  to.  But  as  it  is 
difficult  to  get  a clear  conception  of  a general  law  from  so  many  figures, 
this  relation  is  illustrated  by  a diagram  in  fig.  50.  The  cylinder,  A,  is 
supposed  to  hold  just  To  of  a pound  of  steam,  at  atmospheric  pres- 
sure, or  15  lbs.  absolute  per  square  inch.  If  now  the  piston,  P,  was  in  the 
position  represented  in  fig.  50,  and  of  a pound  of  water  was  put 
into  the  cylinder,  and  heat  was  applied  to  it,  it  would  be  necessary  to  heat 
the  water  to  212  degrees  before  it  will  boil.  To  represent  this  heat,  the  ver- 
tical line,  24  O',  is  extended  below  the  horizontal  line,  24'  O'.  To  heat 
TV  of  a pound  of  water  to  212  degrees  takes  21.2  units  of  heat,  which  is  laid 
off  from  o’  to  o”  to  the  scale  represented  by  the  horizontal  lines.  But,  as 
shown  in  the  table  in  the  appendix,  after  the  water  begins  to  boil,  96.6 
more  units  of  heat  must  be  added  to  it  to  convert  it  all  into  steam  of 
atmospheric  pressure.  This  number  of  units  of  heat  is,  therefore,  laid  off 
from  o”  to  o'".  If  the  piston  is  moved  to  12  12',  the  middle  of  the  cylinder, 
and  of  a pound  of  water  is  again  put  into  it,  and  it  is  all  converted 
into  steam,  it  will  have  a pressure  of  30  lbs.  per  square  inch,  as  it  occupies 
only  half  the  volume  that  the  same  quantity  of  steam  did  before.  To 
make  water  boil  under  a pressure  of  30  lbs.,  it  must  be  heated  to  a tem- 
perature of  250.4  degrees,  which  in  this  case  will  require  25  units  of  heat, 
which  is  laid  down  from  12'  to  12".  To  convert  the  water  into  steam, 
after  it  begins  to  boil,  will  require  93.9  more  units  of  heat,  which  is  also 
laid  down  from  12"  to  12'".  In  the  same  way  the  total  heat  to  boil  and 
.convert  of  a pound  of  water  into  steam  of  60  and  120  lbs.  pres- 
sure, is  taken  from  the  table  in  the  Appendix,  and  laid  down  on  18'  18'" 
and  21'  21'",  and  the  two  curves,  21"  18"  12"  0"  and  21'"  18'"  12'"  O'",  are 
drawn  through  the  points  which  have  been  laid  down.  The  vertical  dis- 
tance of  the  one  curve,  from  24'  O',  represents  the  heat  required  to  boil 
of  a pound  of  water  at  the  pressures  indicated  by  the  curve, 
fl’"  fl"  fl'  above,  and  the  vertical  distance  of  the  curve,  21'"  18'"  12'"  O'", 
from  24'  O’,  represents  the  total  units  of  heat  required  to  convert 
of  a pound  of  water  into  steam  of  a volume  indicated  by  the  horizontal  dis- 
tance of  any  point  of  the  curve  from  24'  24'",  and  when  pressure  is  indi- 
cated by  the  expansion  curve  above.  This  curve,  and  the  heat  diagram, 
may  be  very  conveniently  combined,  by  adding  the  latter  below  the  vacuum 
line,  as  shown  in  fig.  51.  The  relation  of  the  volume  pressure  and  total 
heat  is  thus  shown  very  clearly. 


Fig.  52.  Cylinder,  Piston  and  Steam  Indicator.  Scale 


The  Expansive  Action  of  Steam. 


59 


QUESTION  107.  What  is  the  relative  quantity  of  heat  required  to  convert 
a given  weight  of  water  into  steam  of  different  pressures  ? 

Answer.  As  has  been  stated  the  total  quantity  of  heat  required  to  con- 
vert 1 lb.  of  water  under  different  pressures  into  steam  is  given  in  the 
table  in  Appendix  I.  From  this  table  it  may  be  learned  that  it  takes 
1,178.1  units  of  heat  to  convert  1 lb.  of  water  into  steam  of  atmospheric 
pressure,  and  only  39  units  more  is  required  to  increase  the  pressure  to  120 
lbs.  absolute,  while  an  addition  of  17.2  units  would  then  double  the  pres- 
sure, or  make  it  240  lbs.  The  slight  addition  to  the  temperature  required 
to  generate  steam  of  high  pressure,  is  also  shown  in  the  heat  diagram  in 
figs.  50  and  51.  The  relative  quantity  of  heat  required  to  generate  steam 
of  different  pressures  is  a fact  of  very  great  importance  in  relation  to 
the  economical  use  of  steam,  and  which  will  be  more  fully  explained 
farther  on. 

Question  108.  How  can  we  determine  by  experiment  the  pressure  of 
the  steam  in  the  cylinder  of  a steam  engine  at  all  points  of  the  stroke  of  the 

piston  ? 

Answer.  By  the  use  of  an  instrument  made  for  that  purpose,  called  an 
indicator.  Its  action  can  be  best  explained  by  supposing  that  we  have  a 
small  cylinder,  C,  with  a piston,  T,  fig.  52  (shown  on  an  enlarged  scale  in 

a, .1 


Fig.  53.  Steam  Indicator.  Scale  *4  in.=l  in. 

fig.  53),  and  that  the  cylinder  is  connected  by  a pipe,  U , to  the  front  end, 
f,  of  the  cylinder,  A , so  that  when  steam  is  admitted  to  that  end,  it  will 
be  conducted  to  C,  through  the  pipe,  U.  Over  the  small  piston,  T \ and 


60 


Catechism  of  the  Locomotive. 


attached  to  it  is  a spiral  spring,  j,  which  is  compressed  when  the  piston 
rises,  and  extended  when  it  falls.  To  the  top  of  the  piston-rod,  V,  fig.  53, 
a pencil,  W,  is  attached.  Behind  this  pencil  we  will  suppose  there  is  a 
card,  a b d c,  and  that  this  card  is  so  arranged  that  it  can  slide  horizontally 
and  in  contact  with  the  pencil  point.  With  only  the  pressure  of  the 
atmosphere  above  and  below  the  piston,  T,  the  spring  would  be  neither 
compressed  or  extended,  and  the  piston  would  then  stand  in  the  position 
shown  in  fig.  53.  If,  now,  we  move  the  card  horizontally,  the  pencil  will 
draw  the  atmospheric  line,^  h.  We  will  now  suppose  that  the  tension  of 
the  spring  is  such  that  a pressure  of  10  lbs.  per  square  inch  above  or  below 
the  piston  will  either  extend  or  compress  the  spring  £ inch.  In  other 
words,  every  pound  of  pressure  per  square  inch  in  the  piston  will  move  it 
of  an  inch.  If  we  could  produce  a vacuum  under  the  piston,  it  would 
be  pressed  down  by  the  atmosphere  above  it  ££,  or  £ of  an  inch.  If,  when 
it  is  thus  depressed,  we  again  slide  the  card  along  in  contact  with  the 
pencil  point,  it  will  draw  the  vacuum  line,  e f.  Assuming  that  we  have 
drawn  these  two  lines,  and  that  the  piston  and  card  are  in  the  position 
shown  in  figs.  52  and  53,  we  will  then  suppose  that  a reciprocating  motion 
can  be  given  to  the  card  by  the  lever,  L M N,  fig.  52,  which  is  pivoted,  at 
M,  and  attached,  at  N,  to  the  cross-head  by  a short  connecting-rod,  F. 
It  is  obvious  that  by  connecting  the  upper  end,  L,  of  the  lever,  by  a rod, 
L e,  to  the  card,  abed,  the  latter  will  be  moved  backwards  and  forwards 
by  the  motion  of  the  piston,  B,  and  cross-head,  F,  and  that  the  motion  of 
the  card  will  be  simultaneous  with  that  of  the  piston,  but  of  shorter  stroke. 
We  will  assume  that  the  stroke  of  the  card  is  equal  to  the  length  of  the 
atmospheric  and  vacuum  lines,  g h and  e f,  fig.  53.  If,  now,  the  piston 
being  at  the  beginning  of  the  stroke,  as  shown  in  fig.  52,  steam  of  85  lbs. 
effective  pressure  per  square  inch  (which  is  equal  to  100  lbs,  absolute 
pressure)  is  admitted  into  the  cylinder,  A,  it  will  be  conveyed  through  the 
pipe,/  U,  to  the  cylinder,  C,  and  will  force  up  the  piston  f-f  or  2£  inches 
above  the  atmospheric  line,  or  or  2£  inches  above  the  vacuum  line,  as 
shown  in  fig.  54,  and  the  pencil  will  draw  a vertical  line,  g i,  on  the  card 
(represented  by  a dotted  line  in  fig.  54).  We  will  suppose  further  that 
steam  is  admitted  during  8 inches  of  the  stroke  and  is  then  cut  off. 
When  the  piston,  B,  fig.  52,  has  moved  that  distance,  which  is  £ of  its 
stroke,  the  card  will  also  have  moved  £ of  its  stroke,  and  will  stand 
in  relation  to  the  pencil  in  the  position  represented  in  fig.  55,  and  as 
the  absolute  steam  pressure  in  the  cylinder  was  maintained  at  100  lbs. 
while  the  card  was  moving  that  distance,  the  pencil  will  have  drawn  a 


Fig.  54. 


Steam  Indicator  Cards.  Scale  J4  in.— 1 in. 


62 


Catechism  of  the  Locomotive. 


horizontal  line,  ij.  The  steam  is  now  cut  off  and  begins  to  expand,  and 
its  pressure  is  thereby  reduced.  When  the  piston  of  the  engine  is  at  half- 
stroke, the  card  will  also  be  at  half-stroke,  and  the  steam  will  be  expanded 
from  8 to  12  inches  of  the  stroke.  By  the  rule  given  in  the  answer  to 
question  65,  its  absolute  pressure  would  then  be  66-flbs.,  and  the  indicator- 
piston  will  then  be  pressed  down  by  the  spring,  so  that  the  pencil  will 
stand  in  the  position  shown  in  fig.  56,  or  of  an  inch  above  the 

atmospheric  line.  The  pencil  meanwhile  will  have  drawn  the  curved 
line,/  k.  When  the  piston  has  moved  16  inches,  the  steam  will  be  ex- 
panded to  double  its  volume,  and  its  absolute  pressure  will  therefore 
be  50  lbs.,  and  consequently  the  pencil  will  stand  ££,  or  1£  inches 
above  the  atmospheric  line,  as  shown  in  fig.  57,  and  the  pencil  will  have 
continued  the  curve,/  k to  /.  At  20  inches  the  steam  will  have  40  lbs., 
and  at  the  completion  of  the  stroke  38f  lbs.  absolute  pressure,  and  the 
pencil  will  have  completed  the  curve,  / kl  m n,  as  shown  in  figs.  58  and  59. 
This  is  the  expansion  curve , which  has  already  been  described,  and  its  form 
approximates  to  what  mathematicians  call  a hyperbolic  curve.  If  the  steam 
is  exhausted,  the  indicator-piston  will  descend  and  carry  the  pencil  down  to 
the  atmospheric  line,  and  the  vertical  line,  n h , fig.  60,  will  be  drawn.  On 
the  return  stroke,  after  the  steam  is  exhausted  from  the  engine  cylinder, 
A , fig.  52,  the  pencil  would  draw  the  atmospheric  line,  h g,  fig.  60,  thus 
showing  that  there  is  no  steam  pressure  under  the  piston. 

Such  a diagram  is  called  an  indicator  diagram*  In  practice  there  are 
a great  many  influences  which  modify  it,  such  as  condensation,  perform- 
ance of  work,  imperfection  of  valve  gear,  etc.,  but  for  the  present  these 
are  disregarded. 

Question  109.  How  can  we  ascertain  the  pressure  of  the  steam  for 
any  point  of  the  stroke  from  such  a diagram  ? 

Answer.  By  measuring  the  vertical  distance  of  the  expansion  curve  (fig. 
60)  from  the  vacuum  or  the  atmospheric  line,  as  for  example  8 /,  12  k, 
16  /,  20  m.  As  the  indicator  spring  is  extended  or  compressed  of  an 
inch  f for  every  pound  of  pressure  per  square  inch,  either  above  or  be- 
low the  indicator-piston,  if  we  construct  a scale,  S S,  fig.  60,  divided 
into  divisions  of  ^ of  an  inch  each,  one  of  them  will  represent  1 lb. 

* The  indicator  used  in  practice,  to  show  the  action  of  the  steam  in  the  cylinders  of  steam 
engines,  differs  essentially  in  its  construction  from  that  which  we  have  described.  The  princi- 
ples of  operation  are,  however,  the  same  in  both.  The  construction  of  indicators  is  explained 
in  another  chapter. 

+ Indicator  springs  are  used  of  various  degrees  of  tension,  in  proportion  to  the  steam  pressure 
to  be  indicated. 


The  Expansive  Action  of  Steam. 


63 


of  pressure  per  square  inch  if  measured  vertically  from  the  atmospheric 
or  vacuum  line.  If  we  sub-divide  the  vacuum  line  with  the  same  num- 
ber of  parts  as  there  are  inches  in  the  stroke  of  the  piston  (see  fig.  61) 
we  can  draw  vertical  lines  from  these  points  and  thus  determine  the  pres- 
sure by  comparing  the  length  of  such  lines  with  the  scale,  S S,  fig.  60. 
Thus,  the  line,  8 j,  measures  of  an  inch,  thus  showing  that  the 
absolute  steam  pressure  at  8 inches  of  the  stroke  was  100  lbs.  per  square 
inch ; the  line  12  k measures  ^-64  g"?  of  an  inch,  thus  showing  that  at  12 
inches  of  the  stroke  the  steam  pressure  was  66f  lbs.  At  16,  20  and  24 
inches  of  the  stroke  the  vertical  lines  measure  and  334%'3- ; and, 

therefore,  the  number  of  fortieths  represents  the  pounds  of  steam  pressure 
when  the  piston  was  at  the  points  of  the  stroke  named.  Similar  measurements 
could  be  made  from  other  points,  such  as  2,  6,  10  or  any  other  number  of 
inches  of  the  stroke.  Of  course,  if  we  measure  from  the  vacuum  line  we 
will  have  the  absolute  steam  pressure,  or  the  pressure  above  a vacuum , as 
it  is  sometimes  called ; if  we  measure  from  the  atmospheric  line  we  will 
have  the  effective  pressure,  or  the  pressure  above  the  atmosphere. 

Question  110.  How  can  we  determine  the  average  pressure  during  the 
whole  stroke  of  steam  which  works  expansively  ? 

Answer.  This  can  be  determined  approximately  by  the  following 
method : In  the  first  place,  divide  the  vacuum  line  (fig.  61)  into  any  num- 
ber of  equal  divisions,  say  six.  From  the  points  of  division,  4,  8,  12,  16 
and  20,  which  in  this  case  correspond  with  the  points  which  represent 
inches  of  the  stroke,  draw  perpendicular  lines,  which  will  divide  the  indi- 
cator diagram  into  six  divisions.  It  is  obvious  that  during  the  time  the 
steam  is  working  full  stroke  the  pressure  is  uniformly  100  lbs.  absolute. 
While  the  piston  is  moving  from  8 to  12  inches,  the  pressure  falls  from  100 
to  66$  lbs.,  so  that  at  10  inches  we  have  very  nearly  the  average  pressure 


Fig.  61.  Steam  Indicator  Diagram. 

during  the  period  named.  So  from  12  to  16,  16  to  20  and  20  to  24  the 
average  is  nearly  57.1,  44.4  and  36.3  lbs.,  respectively.  By  adding  to- 
gether the  pressures  in  the  middle  of  each  one  of  a number  of 


64. 


Catechism  of  the  Locomotiv 


EQUAL  DIVISIONS  OF  THE  STROKE  AND  DIVIDING  BY  THE  NUMBER  OF 
DIVISIONS,  WE  WILL  OBTAIN  APPROXIMATELY  THE  AVERAGE  ABSOLUTE 
PRESSURE  DURING  THE  WHOLE  STROKE.  TO  GET  THE  AVERAGE  EFFEC- 
TIVE PRESSURE,  DEDUCT  THE  ATMOSPHERIC  PRESSURE  FROM  THE 
result.  The  calculation  would,  in  the  above  case,  be  as  follows : 

100  lbs. 

100  “ 

80  “ 

57.1 

44.4 

36.3 

' 6)417.8 

69.6=average  absolute  pressure. 

15 

* 

54.6=average  effective  pressure. 

A more  accurate  way  of  calculating  the  average  or  mean  pressure,  as  it 
is  called,  when  steam  is  used  expansively,  and  the  one  which  is  usually 
employed,  is  to  divide  the  length  of  the  piston’s  stroke  in  inches 

BY  THE  NUMBER  OF  INCHES  AT  WHICH  THE  STEAM  IS  CUT  OFF:  THE 
QUOTENT  IS  THE  RATIO  OF  EXPANSION.  GET  THE  HYPERBOLIC  LOGA- 
RITHM OF  THE  RATIO  OF  EXPANSION  FROM  THE  TABLE  OF  LOGARITHMS 

(in  Appendix  II.),  add  1 to  it,  and  divide  the  sum  by  the  ratio  of 

EXPANSION  AND  MULTIPLY  THE  QUOTENT  BY  THE  MEAN  ABSOLUTE 
STEAM  PRESSURE  IN  THE  CYLINDER  DURING  ITS  ADMISSION.  THE  RE- 
SULT WILL  BE  THE  MEAN  ABSOLUTE  PRESSURE  DURING  THE  STROKE. 
TO  GET  THE  MEAN  EFFECTIVE  PRESSURE,  DEDUCT  THE  ATMOSPHERIC 
PRESSURE. 

The  calculation  for  the  above  example  would  be  as  follows  : 

24 

— =3=ratio  of  expansion. 

8 

1.0986  -f  1 

x 100=69. 95=mean  absolute  pressure. 

3 

69.95 — 15=54.95=mean  effective  pressure. 

Question  111.  How  can  the  power  which  a locomotive  will  exert  be  in- 
creased or  diminished  in  proportion  to  the  work  to  be  done  ? 


The  Expansive  Action  of  Steam. 


65 


Answer.  It  can  be  done  either  by  “throttling”  the  steam,  that  is  by 
opening  the  throttle-valve  only  a short  distance,  so  that  the  pressure  in 
the  cylinders  will  be  less  than  that  in  the  boiler ; or,  the  steam  can  be 
worked  expansively  by  allowing  it  to  enter  the  cylinders  during  a portion 
only  of  the  stroke,  and  the  flow  can  then  be  “cut  off,”  as  it  is  called,  that 
is,  the  steam  passages  through  which  the  steam  enters  the  cylinders  are 
closed  when  the  piston  has  moved  through  a part,  say  a half,  a third  or  a 
quarter  of  the  stroke,  and  the  steam  then  expands  during  the  rest  of  the 
stroke.  As  the  work  which  a locomotive  must  do  is  constantly  varying, 
it  is  important  to  know  whether  it  is  more  advantageous  to  throttle  the 
steam  or  work  it  expansively. 

Question  112.  What  advantages  result  from  using  steam  expan- 
sively ? 

Answer.  The  most  important  one  is  that  considerably  more  work  can 
be  done  with  a given  amount  of  steam  and  fuel  if  the  steam  generated 
thereby  is  worked  expansively  than  if  it  is  not. 

Next,  the  pressure  exerted  on  the  crank  is  equalized  by  expansive  action, 
and  lastly,  the  strain  and  shocks  to  the  mechanism  which  are  produced  by 
the  rapid  motion  of  the  piston  and  other  reciprocating  and  revolving  parts 
of  the  engine  are  very  much  diminished  by  allowing  the  steam  to  expand, 
and  thus  become  reduced  in  pressure  during  the  latter  part  of  the  stroke. 

The  expansive  force  of  steam  represents  energy  or  capacity  of  doing 
work,  and,  therefore,  if  we  allow  it  to  escape  with  a comparatively  high 
pressure  without  doing  work,  it  is  a waste  of  energy. 

Question  113.  What  question  must  usually  be  considered  in  operating 
locomotives  ? 

Answer.  It  must  be  determined  whether  it  is  more  economical  to  use 
steam  of  a comparatively  high  pressure  in  the  boiler  and  a high  degree  of 
expansion  in  the  cylinders,  or,  whether  the  pressure  of  the  steam  should 
be  reduced  before  it  enters  the  cylinders,  by  partially  closing  the  throttle- 
valve,  and  then  expanding  it  less  in  the  cylinders. 

Question  114.  How  can  the  advantages  of  high  boiler  pressure  and 
high  degrees  of  expansion  over  lower  pressure  and  less  expansion  be  shown  ? 

Answer.  By  comparing  the  work  done  by  a given  weight  of  steam  of 
different  volumes  and  pressures.  Thus,  in  fig.  62,  the  shaded  area  repre- 
sents the  volume  of  of  a pound  of  steam  of  120  lbs.  pressure  per 
square  inch,  which  is  supposed  to  be  admitted  into  the  cylinder,  shown  in 
fig.  50,  which  is  15.4  inches  in  diameter,  and  the  piston  has  24  inch  stroke. 
The  quantity  of  steam  represented  in  fig.  62  would  occupy  of  the 


PRESSURE  PRESSURE  ^ PRESSURE 


Fig  63. 


The  Expansive  Action  of  Steam. 


67 


cylinder  or  3 inches  of  its  length*  and  can  therefore  expand  eight 
times.  By  the  rule  given  in  answer  to  Question  110,  we  find  that  under 
these  conditions  the  average  pressure  above  the  atmosphere  during  the 
whole  stroke  will  be  31.2  lbs.  The  same  weight  of  steam  of  60  lbs.  pres- 
sure will  fill  ^ of  the  cylinder,  as  shown  by  the  shaded  area  in  fig.  63,  and 
if  expanded  four  times,  will  have  an  average  pressure  of  20.8  lbs.  At  30 
lbs.  pressure,  of  a pound  of  steam  will  fill  half  the  cylinder,  as  shown 
in  fig.  64,  and  if  expanded  twice,  will  have  an  average  pressure  of  10.4 
lbs.  The  total  heat  of  ^ of  a pound  of  steam  at  the  different  pressures 
assumed  would  be  as  follows  : 


At  120  lbs.  pressure  per  square  inch 118.5  units. 

“ 60  “ “ “ “ 117.0  “ 

“ 30  “ “ “ “ 115.7  “ 


The  area  of  a piston  15.4  inches  diameter  is  186.2  square  inches,  and  its 
stroke  in  this  instance  is  2 feet.  By  multiplying  the  average  pressure  in 
pounds  per  square  inch  into  the  area  of  the  piston  in  square  inches,  will 
give  the  total  average  pressure  on  the  piston,  and  by  multiplying  this  by 
the  stroke  in  feet,  will  give  the  number  of  foot-pounds  of  work  done 
during  each  stroke,  as  follows : 

31.2  x 186.2  x 2 = 11,618.8  foot  pounds. 

20.8  x 186.2  x 2 = 7,745.9  “ 

10.4  x 186.2  x 2 = 3,872.9  “ 

If  we  now  divide  the  amount  of  work  done  in  foot-pounds  by  the  units 

of  heat  in  the  steam,  it  will  show  the  amount  of  work  done  per  unit  of 
heat,  and  show  the  theoretical  difference  there'  is  in  working  steam  of  a 
high  pressure  and  a high  degree  of  expansion,  compared  with  the  use 
of  steam  of  low  pressure  and  corresponding  expansion.  Such  a calcula- 
tion has  been  made  and  is  given  in  the  following  table  : 


* In  making  these  calculations  the  volume  of  one-tenth  of  a pound  of  steam  of  atmospheric 
pressure  has  been  taken  at  4,466.8  cubic  inches,  which  is  the  capacity  of  a cylinder  of  the  dimen- 
sions given.  The  volume  of  steam  has  then  been  assumed  to  be  inversely  proportional  to  its 
pressure.  This  is  not  exactly  correct  as  the  volume  of  steam  of  greater  pressure,  owing  to  its 
higher  temperature,  is  more  than  has  been  given.  The  data  have  been  assumed  only  to  illus- 
trate a principle  and  not  to  reach  precise  results. 


68 


Catechism  of  the  Locomotive. 


PRESSURE,  TOTAL  HEAT  AND  WORK  DONE  DURING  1 STROKE  BY  TV 

Of  a pound  of  steam  with  different  ratios  of  expansion  in 
A CYLINDER  15.4  INCHES  DIAMETER  AND  2 FEET  STROKE  OF  PISTON. 


Absolute 

Initial 

Pressure. 

Average 

Pressure. 

Ratio 

of 

Expansion. 

Total 

Heat. 

Work  Done. 

Work  done 
per 

UNIT  OF  HEAT. 

Lbs.  per  sq. 
inch. 

Lbs.  per  sq. 
inch. 

Units. 

Foot-pounds. 

Foot-pounds. 

120 

31.2 

8 

118.5 

11,681.8 

98.5 

60 

20.8 

4 

117.0 

7,745.9 

65.3 

30 

10.4 

2 

115.7 

3,872.9 

33.4 

From  the  calculations — the  results  of  which  are  given  in  the  last  column 
of  the  table — it  will  be  seen  that  with  steam  of  120  lbs.  pressure  expanded 
eight  times,  a given  quantity  of  heat  should  do  nearly  three  times  as  much 
work  as  the  same  quantity  of  heat  will,  if  steam  of  30  lbs.  pressure  is  used 
and  expanded  to  twice  its  volume. 

Question  115.  Can  the  principle  of  the  increased  efficiency  of  steam 
with  increased  pressures  be  shown  graphically  ? 

Answer.  Yes;  this  can  be  shown  by  a comparison  of  figs.  62,  63  and 
64.  In  fig.  64  the  shaded  area,  jo  p'  12  0,  represents  the  volume  and  pres- 
sure of  XV  of  a pound  of  steam  of  30  lbs.  absolute  pressure,  and  the  area, 
jo  p'  p ij,  represents  the  useful  work  which  it  will  do ; its  total  heat  is 
115.7  units.  In  fig.  63,  60  p"  6 o,  represents  the  volume  and  pressure  «of  TV 
of  a pound  of  steam  of  60  lbs.  pressure.  The  total  heat  of  this  is  117 
units,  and  the  area,  60 p"  p 13,  represents  the  work  done  by  it.  It  will  be 
seen,  then,  that  by  the  addition  of  1.3  units  of  heat  to  the  steam  repre- 
sented in  fig.  64,  that  the  work  done  by  it  would  have  been  increased  by 
an  amount  equal  to  the  area,  60  p"  p'  jo,  in  fig.  64.  By  comparing  fig.  62 
with  64  it  will  be  seen  that  the  shaded  area,  120  p'"  j 0,  represents  the 
volume  and  pressure  of  TV  lb.  of  steam  of  120  lbs.  pressure,  and  the  area, 
120  p’”  p’  p ij,  the  work  done  by  it,  and  that  its  total  heat  is  118.5  units. 
Therefore,  if  2.8  units  of  heat  had  been  added  to  the  steam  represented  in 
fig.  64,  its  energy  would  have  been  increased  by  the  area,  120  p"'  p"  p'  3°. 

Question  116.  Can  it  be  shown- in  any  other  way  why  it  is  economical 
to  work  steam  expansively  ? 

Answer.  Yes;  it  can  be  shown  from  the  “total  heat ” contained  in  a 
given  quantity  of  steam  used  expansively  and  that  in  steam  which  has 


The  Expansive  Action  of  Steam. 


69 


been  used  without  expansion,  and  then  comparing  the  two  quantities  with 
the  amount  of  work  done  under  the  two  different  conditions. 

For  the  basis  of  the  calculation,  a cylinder  of  16  inches  diameter,  and 
piston  with  24  inch  stroke,  and  steam  of  100  lbs.  absolute  pressure  cut  off 
at  8 inches  of  the  stroke,  will  be  taken.  It  will  be  supposed,  further,  that 
the  steam  used  is  generated  from  water  of  a temperature  of  60  degrees, 
and  the  total  number  of  units  of  heat  in  the  steam  used  for  each  stroke  of 
the  piston  will  then  be  calculated.  The  area  of  a piston  16  inches  in  di- 
ameter is  201  square  inches ; and  as  the  steam  is  admitted  until  the  piston 
moves  8 inches  of  its  stroke,  therefore,  the  quantity  of  steam  would  be  8 
times  201  cubic  inches,  or 

1,608 

201  x 8 = 1,608  cubic  inches  = cubic  feet. 

1,728 

From  the  table  it  will  be  seen  that  1 cubic  foot  of  steam  of  100  lbs. 
pressure  weighs  0.2307  lbs. ; therefore,  the  weight  of  the  fraction  of  a cubic 
foot  given  above  would  be  calculated  as  follows : 

.2307  x 1,608 

= .2146  lbs.  = weight  of  1608  cubic  inches  of  steam  of  100  lbs. 

1,728 

absolute  pressure. 

From  the  table  it  will  be  seen  that  the  total  heat  above  zero  of  steam  of 
100  lbs.  absolute  pressure  is  1,213.4  degrees.  It  was  explained  in  the 
answer  to  Question  79,  that  1 lb.  of  water  heated  1 degree  is  the 
standard  of  measurement  or  unit  of  heat.  Now,  if  we  have  1 lb.  of 
water  with  a temperature  of  zero,  evidently  it  will  take  1,213.4  u?iits  of  heat 
to  convert  it  into  steam  of  100  lbs.  absolute  pressure.  But  as  the  water 
from  which  our  steam  was  generated  had  a temperature  of  60  degrees,  we 
must  deduct  that  much  from  1,213.4  : 1,213.4 — 60.=l,153.4=units  of  heat 
in  1 lb.  of  steam  of  100  lbs.  absolute  pressure  generated  from  water  of  60 
degrees  temperature. 

If  then  1 lb.  of  steam  has  1,153.4  units  of  heat,  the  following  cal- 
culation will  give  the  units  of  heat  in  .2146  lbs,:  1,153.4  x .2146=247.51 
=units  of  heat  in  .2146  lbs.,  or  1,608  cubic  inches  of  steam  of  100  lbs.  ab- 
solute pressure.  It  was  shown  in  answer  to  Question  110  that  the  average 
pressure  of  steam  of  100  lbs.  cut  off  at  8 inches  of  the  stroke  was  69.95  lbs. 
per  square  inch.  So  that  if  steam  of  100  lbs.  absolute  pressure  is  used  ex- 
pansively it  requires  247.51  units  of  heat  to  produce  an  average  absolute 
pressure  of  69.95  lbs.  per  square  inch  during  the  whole  stroke.  Disregard- 


70 


Catechism  of  the  Locomotive. 


ing  the  small  fraction,  we  will  call  it  70  lbs.  Now,  if  we  admit  steam  of 
this  pressure  through  the  whole  stroke  of  the  piston,  we  will  use  4,824  cubic 
inches.  It  will  be  found  by  a calculation  similar  to  the  above,  that  to 
generate  this  quantity  of  steam  of  70  lbs.  absolute  pressure  from  water  of 
a temperature  of  60  degrees  would  require  527  units  of  heat,  or  more  than 
twice  as  many  as  were  required  to  do  the  same  work  with  steam  of  100 
lbs.  pressure  cut  off  at  8 inches  when  using  it  expansively  during  the  rest 
of  the  stroke. 

There  is  also  an  incidental  advantage  in  working  steam  expansively, 
because  low-pressure  steam  can  be  exhausted  more  quickly  from  a cylin- 
der than  steam  of  a high  pressure,  and  consequently  there  is  less  resistance 
or  back  pressure,  as  it  is  called,  in  the  exhausted  end  of  the  cylinder  to  the 
movement  of  the  piston. 

Question  117.  Does  the  theoretical  economy  in  using  steam  increase 
with  the  pressure  and  the  degrees  of  expansion  ? 

Answer.  Yes;  this  is  shown  in  the  following  table,  in  the  first  column 
of  which  the  number  of  inches  of  the  piston  stroke  is  given  during  which 
steam  is  admitted  to  a cylinder  16  inches  in  diameter  and  24  inch  stroke. 
In  the  second  column  is  given  the  pressure  of  the  steam  or  initial  pres- 
sure, as  it  is  called,  which  must  be  admitted  into  the  cylinder  in  order  to 
produce  a mean  absolute  pressure  of  70  lbs.  per  square  inch  when  it  is  cut 
off  at  the  point  indicated  in  the  first  column.  In  the  third  column  is 
given  the  total  heat  which  is  required  to  generate  the  steam  required  in 
each  case,  and  in  the  last  column  the  percentage  of  saving  is  given,  which 
results  from  the  different  degrees  of  expansion  and  a mean  pressure  of  70 
lbs.  per  square  inch  in  each  case. 

RESULTS  OF  USING  STEAM  EXPANSIVELY. 


Period  of  admission  or  point  of  cut-off. 

Initial  abso- 
lute PRESSURE 
OF  STEAM  IN 

POUNDS  PER 
SQUARE  INCH. 

Total  heat  of 

STEAM  USED,  IN 
UNITS. 

. 

Percentage  of 

SAVING  COM- 
PARED WITH 

FULL  STROKE. 

Full  stroke 

70. 

527. 

18  in.  = Three-quarters  of  the  stroke 

72.5 

408.7 

22H 

12  in.  <=  One-half  “ “ 

82.7 

302.8 

m 

8 in.  = One-third  “ “ 

100. 

247.5 

53 

6 in.  = One-quarter  “ “ 

117.4 

216.6 

58 

4 in.  ■=  One-sixth  “ " 

150.5 

183.8 

65 

3 in.  »=  One-eighth  “ “ 

181.8 

165.8 

68^ 

2 in.  = One-twelfth  “ “ 

241.4 

144.8 

72^ 

The  Expansive  Action  of  Steam. 


71 


From  this  table  it  will  be  seen  that  if  we  could  get  the  full  advan- 
tage of  using  steam  expansively,  22-J  per  cent,  of  heat  would  be  saved 
by  cutting  off  at  f of  the  stroke  and  using  steam  of  72.5  lbs. 
pressure  instead  of  steam  of  70  lbs.  worked  full  stroke.  Cutting  off  at 
^-stroke  and  using  steam  of  82.7  lbs.,  42^-  per  cent,  of  heat  would  be 
saved,  and  cutting  off  at  ^-stroke  with  steam  of  117.4  lbs.,  should  save 
58  per  cent,  of  heat;  and  at  of  the  stroke,  or  expanding  steam  of  241.4 
lbs.  pressure  to  twelve  times  its  volume  would  save  72£  per  cent,  of  heat. 

Question  118.  In  practice  can  we  get  as  much  advantage  from  work- 
ing steam  expansively  as  the  above  calculations  seem  to  show  is  possible  ? 

Answer.  No ; it  is  not  possible  in  steam  engines,  as  they  are  at  present 
constructed,  to  convert  all  the  potential  energy  in  steam  into  actual  work. 
There  is  more  or  less  loss  in  all  engines  from  back  pressure,  clearance  in 
the  cylinders  and  the  loss  of  heat  from  radiation,  and  condensation,  and 
other  causes  is  greater  when  steam  of  a high  pressure  is  expanded  much 
than  when  lower  pressure  steam  is  admitted  through  a greater  part  of  the 
stroke. 

QUESTION  119.  What  effect  does  back  pressure  have  when  steam  is 
worked  expansively  ? 

Answer.  Its  effect  is  to  reduce  the  effective  pressure.  Thus,  in  fig.  62, 
the  effective  pressure,  instead  of  being  46.2  lbs.  per  square  inch,  is  only 
81.2,  owing  to  the  pressure  of  the  atmosphere  on  the  back  of  the  piston. 
If  the  area  of  the  piston  is  186.2  square  inches  and  the  stroke  2 feet,  the  work 
done  in  one  stroke  will  be  equal  to  186.2  x 81.2  x 2=11,618.8  foot-pounds. 
If  there  was  a vacuum  behind  the  piston  so  that  the  effective  pressure  was 
46.2  lbs.  instead  of  31.2,  then  the  work  done  would  be  equal  to  17,204.8 
foot-pounds.  In  locomotives  the  back  pressure  nearly  always  exceeds  the 
atmospheric  pressure,  and  at  high  speeds  is  sometimes  twice  as  great.  If 
the  back  pressure  was  20  lbs.  above  a vacuum  or  5 lbs.  above  the  atmos- 
phere then  under  the  conditions  shown  in  the  diagram,  fig.  62,  the  steam 
pressure  in  front  of  the  piston  from  the  point,  m to  p,  would  be  less  than 
the  back  pressure  behind  it,  as  is  indicated  by  the  black  area,  m n p.  It 
is  obviously  a disadvantage  to  expand  the  steam  below  the  back  pressure, 
as  the  retarding  effort  of  the  latter  is  then  greater  than  the  propelling 
pressure  on  the  opposite  side  of  the  piston. 

There  are  also  other  practical  difficulties  in  the  way  of  using  high  de- 
grees of  expansion.  It  has  been  explained  that,  if  steam  is  cut  off  early  in 
the  stroke  and  the  degree  of  expansion  increased,  the  pressure  and  conse- 
quently the  temperature  of  the  steam  must  also  be  increased  to  do  the 


72 


Catechism  of  the  Locomotive. 


same  amount  of  work.  The  danger  of  explosion  is  greater  with  the 
higher  pressures,  and  stronger  and  more  expensive  boilers  and  machinery- 
are  therefore  needed.  With  steam  of  very  high  temperature  the  metal  of 
the  cylinders,  pistons,  and  valves  becomes  so  much  heated  that  they 
soften,  and  then  the  friction  of  the  one  on  the  other  is  liable  to  cause  them 
to  cut  or  scratch  each  other.  The  high  temperature  at  the  same  time 
destroys  the  oil  or  other  lubricant  used  in  contact  with  the  steam.  It  is 
also  impossible  to  admit  and  cut  off  steam  very  early  in  the  stroke  with 
the  ordinary  mechanical  appliances  used  for  moving  slide-valves  of  loco- 
motives. This  latter  difficulty  and  the  effect  of  expansion  in  equalizing 
the  pressure  on  the  crank  and  lessening  the  strains  and  shocks  on  the 
mechanism  of  the  engine  will  be  more  fully  explained  hereafter. 

Question  120.  How  may  the  amount  of  expansion  that  can  be  made 
practically  useful  be  illustrated  and  explained  ? 

Answer.  It  was  shown  in  answer  to  Question  110,  that  if  steam  of  100 
lbs.  pressure  is  admitted  into  the  cylinder  during  one-third  of  the  stroke, 
and  it  is  allowed  to  expand  during  the  rest  of  the  stroke,  the  mean  effec- 
tive pressure  represented  by  the  indicator  card  shown  in  fig.  61  will  be 
54.95  lbs.  per  square  inch.  As  the  stroke  of  the  piston  is  2 feet,  the  num- 
ber of  foot-pounds  of  work  which  would  be  exerted  for  each  square  inch 
of  area  of  the  piston  during  each  stroke  would  be  54.95x2=109.9.  Let 
ij  nop , fig.  65,  represent  this  card,  and  let  it  be  supposed  that  the  cylin- 
der is  lengthened  so  that  the  piston  will  have  4 feet  stroke  instead  of  2 
feet,  and  that  the  steam  is  expanded  six  times  instead  of  three  times. 
The  indicator  diagram  which  the  steam  would  then  make  would  be  repres- 
ented by  i j n k p.  By  calculating  the  mean  effective  pressure  for  the 
whole  stroke  of  4 feet,  in  the  manner  already  described,  it  will  be  found  to 
be  81.53  lbs.  As  the  pressure  is  exerted  through  4 feet  of  stroke,  the  work 
done  per  square  inch  of  piston  will  be  31.53  x 4=126.12  foot-pounds  or  again 
of  nearly  15  per  cent.  It  should  be  observed  that  to  secure  this  economy 
the  cylinder  and  a number  of  other  parts  of  the  engine  must  be  doubled 
in  size.  If,  as  indicated  by  the  black  area,  fig.  65,  the  back  pressure  was 
double  the  atmospheric  pressure,  as  it  sometimes  is  in  locomotives,  then 
the  steam  pressure  would  fall  below  the  back  pressure  from  c to  k.  The 
loss  by  expansion  would  therefore  be  greater  than  the  gain.  It  will  thus 
be  seen  that  with  a given  amount  of  back  pressure  there  is  no  advantage 
in  carrying  expansion  beyond  a certain  point,  unless  there  is  a correspond- 
ing increase  in  initial  pressure.* 

* The  pressure  of  the  steam  when  it  is  first  admitted  to  the  cylinder  and  before  it  is  cut  off  is 
called  the  initial  pressure. 


The  Expansive  Action  of  Steam. 


73 


QUESTION  121.  What  will  be  the  result , if,  instead  of  increasing  the 
size  of  the  cylinder  and  rate  of  expansion,  we  double  the  “ initial  pres- 
sure ” of  the  steam  which  is  introduced  into  the  cylinder , and  then  cut 
it  off  at  \ of  the  stroke  instead  of  $? 


Answer.  The  effect  of  this' can  be  shown  if  we  draw  a diagram,  Imj  n 
op,  fig.  65,  in  which  the  initial  pressure  represented  by  the  height,  l p,  is  200 
lbs.  absolute,  instead  of  100,  and  the  steam  is  supposed  to  be  cut  off  at  m, 
or  at  4 inches  of  the  stroke,  instead  of  8,  and  the  piston  to  have  a stroke, 
p o,  of  2 feet.  If  the  average  effective  pressure  is  then  calculated  as  before, 
it  will  be  found  to  be  78.06  lbs.  per  square  inch,  so  that  the  work  done  per 
square  inch  of  area  of  the  piston  during  each  stroke  will  be  156.12  foot- 
pounds instead  of  109.9,  or  a gain  of  over  42  per  cent.,  with  steam  of  100 
lbs.  pressure  expanded  three  times.  By  referring  to  the  table  of  the  prop- 
erties of  steam  it  will  be  seen  that  with  100  lbs.  pressure  the  total  heat  is 
1,213.4,  and  with  200  -it  is  1,229.8,  a difference  of  16.4  degrees  or  units,  or 
only  a little  over  H per  cent.  more.  That  is,  theoretically,  by  adding  1£ 
per  cent,  more  heat  to  the  steam  and  expanding  it  twice  as  much,  there  is 
a gain  of  42  per  cent,  in  the  amount  of  work  done.  To  do  this,  though, 


74 


Catechism  of  the  Locomotive. 


the  boiler  and  engine  must  be  made  twice  as  strong  to  resist  these  high 
pressures. 

We  may  assume,  still  further,  that  the  stroke  is  lengthened,  and  the 
steam  of  200  lbs.  pressure  is  expanded  twelve  times,  as  indicated  by  the 
diagram,  Imj  nkft,  and  also  that  the  pressure  is  increased*  to  400  lbs.  with 
the  same  degree  of  expansion  as  shown  by  the  diagram,  s t mj  n o ft,  or 
twenty-four  times  as  represented  by  s t k ft.  In  the  following  table  the 
calculated  results  from  these  high  pressures  and  rates  of  expansion  are 
given : 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

Sd 

zz 

d 

_o 

c 

d 

o 

V 

xs 

c 

u O O 

> <U  <0 

V u 

d 

'c3 

b/3 

'o 

Cylinder. 

< Z)  V 

C/D  U 

£ 3 

PLh  g. 

rt  u 
'Zj  <L> 

•sa 

< C/D 
£ 

nj 

a 

X 

W 

o 

V 

1 

Pi 

£ 

o 

1> 

44 

o 

C A 

Average  cy 
pressure. 

Foot-lbs.  of 
done  per  strol 
each  inch  in  a 
cylinder. 

o 

V 

bJD 

3 

V 

a 

V-4 

V 

fU 

b/D 

C 

V 

C/D 

U 

QJ 

‘o 

PQ 

Size  of 

Strength  of 

a 

100 

3 

Feet. 

2 

54.95 

109.09 

i 

1 

1 

b 

100 

6 

4 

31.53 

126.12 

15 

i 

2 

1 

c 

200 

6 

2 

78.06 

156.12 

42 

2 

1 

2 

d 

200 

12 

4 

43.08 

172.32 

57 

2 

2 

2 

e 

400 

12 

2 

101.00 

202.00 

83 

4 

4 

2 

f 

400 

24 

4 

54.6 

218.4 

100 

4 

4 

4 

Column  6 shows  the  gain  in  foot-pounds  of  work  done  per  square  inch 
of  piston,  and  from  the  increased  steam  pressure  and  higher  rates  of  ex- 
pansion. Column  7 gives  the  percentage  of  gain  in  the  work  done  when 
compared  with  the  results  with  steam  of  an  initial  pressure  of  100  lbs. 
expanded  three  times.  Column  8 gives  the  relative  strength  of  the 
boiler  for  pressures  of  100,  200  and  400  lbs.  Columns  9 and  10  give  the 
relative  sizes  and  the  strength  of  cylinders  required  for  the  pressures  and 
rates  of  expansion  given  in  columns  2 and  8.  From  the  horizontal  line,  b, 
of  the  table,  it  will  be  seen  that,  by  doubling  the  rate  of  expansion,  there 
is  a gain  of  15  per  cent.,  but  the  cylinder  must  then  be  twice  as  large  as 
before.  This  means  an  increase  in  size  and  strength  of  other  parts.  To 
gain  42  per  cent.,  by  doubling  the  pressure  and  rate  of  expansion,  as  shown 
in  the  line  marked  c,  the  boiler  and  cylinder  must  both  be  doubled  in 
strength.  A gain  of  57  per  cent.,  by  doubling  the  pressure  and  quadrupl- 
ing the  rate  of  expansion,  requires  the  strength  of  boiler,  and  size  and 


The  Expansive  Action  of  Steam. 


75 


strength  of  engine,  all  to  be  doubled,  and  the  gain  of  100  per  cent,  in  the  last 
line  compels  the  strength  of  boiler,  and  strength  and  size  of  cylinder  all 
to  be  quadrupled.  From  this  table  it  is  obvious  that  we  soon  reach  a 
point  at  which  increasing  the  steam  pressure  and  rate  of  expansion  in- 
volves so  much  expense  for  the  larger  size  and  strength  of  boiler  and 
engine,  that  the  gain  in  the  work  done  will  not  pay  for  the  increased  cost. 

An  inspection  of  the  diagram  will  also  show  that  it  requires  a compara- 
tively small  increase  of  back  pressure  above  the  atmosphere  to  neutralize 
the  advantages  of  the  high  degrees  of  expansion.  As  there  always  is  a 
considerable  amount  of  back  pressure  in  locomotives,  especially  at  high 
speeds,  it  will  be  seen  that  there  is  no  economy  in  carrying  expansion 
beyond  certain  limits.  It  should  also  be  explained  that  there  are  other 
causes  which  have  an  effect  in  the  economy  of  expansion.  In  every 
engine  there  is  always  a very  considerable  loss  of  heat  from  radiation, 
conduction,  and  from  the  conversion  of  heat  into  work,  and  probably  from 
causes  not  yet  perfectly  understood. 

Question  122.  What  is  meant  by  the  “ clearance  ” of  a piston  and 
cylinder  ? 

Answer.  When  the  piston  of  an  engine  is  at  the  end  of  its  stroke  there 
is  always  some  space  left  between  it  and  the  cylinder-head  so  that  there 
will  be  no  danger  of  the  one  striking  the  other.  The  distance  between 
the  piston  and  cylinder-head  at  the  end  of  the  stroke  is  called  the  “clear- 
ance.” Besides  this  space,  the  passages  between  the  valve-face  and  the 
end  of  the  cylinder  must  also  be  filled  with  steam  before  the  piston  begins 
its  stroke.  The  whole  of  the  spaces  between  the  piston  and  valve-face  is 
called  the  clearance  space. 

Question  123.  What  effect  does  the  steam  which  is  required  to  fill  the 
clearance  spaces  have  on  the  piston? 

Answer.  To  explain  this  it  will  be  supposed  that  the  clearance  space  at 
each  end  of  the  cylinder  is  equal  to  of  its  cubical  contents.  If 
steam  was  used  at  full  pressure  during  the  whole  stroke  of  the  piston,  it 
would  take  tV  more  steam  for  each  stroke  to  move  the  piston, 
and  this  steam  would  be  wasted.  But  if  the  steam  was  allowed  to  expand 
in  the  cylinder,  then  that  which  fills  the  clearance  spaces  would  expand 
as  well  as  that  in  the  cylinder,  and  would  thus  exert  pressure  on  the 
piston.  To  illustrate  this,  let  a b 24  0,  fig.  66,  represent  a diagram  to  show 
the  action  of  steam  in  a cylinder.  It  will  also  be  supposed  that  a d e 0 
represents  the  clearance  space  = the  contents  of  the  cylinder.  It 
may  now  be  supposed  that  while  the  steam  is  flowing  in  to  fill  this 


76 


Catechism  of  the  Locomotive. 


space  the  piston  is  standing  still,  and  the  steam,  therefore,  does  no  work 
during  this  period.  When  the  clearance  space  is  filled  with  steam  of 
initial  pressure,  the  piston  begins  to  move  until  it  reaches  p"\  where  the 
steam  is  cut  off  and. begins  to  act  expansively.  If  now  only  that  part  of 
the  cylinder,  represented  by  the  area  a p"'  3 0,  was  filled  with  steam, 
an  expansion  curve,  p’"  p"  p'  p , like  that  represented  by  the  dotted 
line  in  fig.  62,  would  represent  the  pressure  of  the  steam.  But  the  steam 
which  expands,  after  it  is  cut  off,  is  not  only  that  which  fills 


the  space,  a p’"  3 0,  but  that  which  fills  the  space,  d p'"  3 e. 
Consequently,  its  expansive  action  is  the  same  as  though  the  cyl- 
inder had  been  lengthened  2 inches,  and  its  contents  were  equal  to 
d b 24  e,  and  5 instead  of  3 inches  was  filled  with  steam  of  initial  pressure. 
Therefore,  the  curve,  p'"  f g h,  represents  the  pressure  of  the  steam  dur- 
ing expansion.  The  space  between  the  two  curves  shows  the  effect  of  the 
expansive  action  of  the  steam  contained  in  the  clearance  space. 

Question  124.  1 s there  any  waste  of  steam  on  account  of  the  clearance 

spaces  ? 

Answer.  Yes;  if  live  steam  must  be  admitted  to  fill  these  spaces  it  does 
no  useful  work  while  it  is  being  admitted. 

Question  125.  Can  the  loss  caused  by  the  clearance  spaces  be  reduced  in 
any  way  ? 

Answer.  Yes;  by  closing  the  exhaust  passage  in  the  cylinder  before  the 
end  of  the  stroke  of  the  piston,  so  that  the  steam  thus  enclosed  in  front 
of  the  piston  will  be  compressed  and  fill  the  clearance  spaces  at  a 
pressure  and  temperature  equal  to,  or  nearly  equal  to  that  of  the  steam 


The  Expansive  Action  of  Steam. 


77 


which  enters  the  cylinder.  This  is  illustrated  in  fig.  66,  in  which  it  is  sup- 
posed that  there  is  a back  pressure  of  20  lbs.  per  square  inch,  and  when 
the  piston  is  moving  in  the  direction  of  the  dart,  D,  the  exhaust-port  is 
closed  at  i,  while  the  piston  must  still  move  10  inches,  before  reaching  the 
end  of  its  stroke.  The  steam  of  20  lbs.  pressure  in  front  of  it  must,  there- 
fore, be  forced  into  the  clearance  space,  and  will  be  compressed  six  times, 
as  indicated  by  the  curve,  ij  k a , so  that  at  the  beginning  of  the  stroke  its 
pressure  will  be  120  lbs.,  or  equal  to  that  of  the  entering  steam.  At  the 
beginning  of  the  stroke  the  clearance  space  will  thus  be  filled,  so  that  no 
live  steam  will  be  wasted,  with  the  exception  of  the  loss  due  to  escape  of 
heat,  leakage  and  friction,  the  steam  will  give  out  as  much  power  by  expan- 
sion, as  was  required  to  compress  it,  so  that  there  will  be  little  waste  due 
to  compression,  if  the  clearance  space,  the  compression,  and  the  back 
pressure,  are  properly  proportioned  to  each  other. 

QUESTION  126.  What  other  reasons-  are  there  why  very  high  pressures 
and  high  degrees  of  expansion  are  not  economical  nor  practicable  ? 

Answer.  If  steam  of  high  pressure  is  admitted  into  a cylinder,  the 
difference  between  its  temperature  and  that  of  the  cylinder  during  the 
period  when  the  steam  is  exhausted  is  so  great  as  to  condense  a consider- 
able portion  of  the  steam.  This  loss  from  condensation  increases  with 
the  difference  between  the  temperature  of  the  steam  admitted  and  that  of 
the  cylinder  during  the  time  that  it  is  exhausted.  This  loss  finally  equals 
or  exceeds  what  is  gained.  There  is  also  the  difficulty  that  the  valve-gear 
which  is  now  generally  used  will  not  admit  steam  freely  to  the  cylinders 
and  cut  it  off  short ; and  next,  high  rates  of  expansion  require  either  large 
cylinders  or  high  initial  pressure.  In  either  case,  it  means  that  the  pro- 
pelling force,  exerted  to  turn  the  wheels,  will  be  excessive  during  some 
portions  of  each  revolution  of  the  wheels,  and  will  thus  cause  them  to 
slip.  This  will  be  explained  in  a future  chapter. 

QUESTION  127.  In  what  way  may  steam  of  higher  pressure,  and  higher 
degrees  of  expansion  be  used,  than  are  practicable  with  the  ordinary  means 
employed  ? 

Answer.  This  may  be  done  by  compounding  the  engines — that  is  by 
working  steam  of  a high  tension  and  reducing  its  pressure  by  expansion 
in  small  cylinders,  and  then  allowing  it  to  escape  into  larger  cylinders 
when  it  is  worked  over  and  expanded  again.  This  method  is  now  very 
generally  employed  in  marine  and  stationary  engines  and  results  in  great 
economy.  Compound  locomotives  are  also  largely  used  in  Europe,  and 
at  present,  1890,  to  some  extent,  experimentally,  in  this  country. 


CHAPTER  VIII. 


THE  SLID  E-V  A L V E . 

Question  128.  How  is  an  ordinary  slide-valve  constructed? 

Answer.  The  general  construction  of  a slide-valve  was  explained  in 
answer  to  Question  89.  Such  a valve  is  represented  by  figs.  67  and  68 ; fig. 
67  being  a longitudinal  section  and  fig.  68  a plan. 

Question  129.  What  is  meant  by  the  lap  of  a valve  ? 

Answer.  The  “ lap  " of  a valve  is  that  portion  of  it  which  overlaps  the 
steam-ports,  when  it  stands  midway  over  the  valve-face.  Thus,  in  fig.  67, 
the  parts,  L L',  shaded  with  cross-lines,  and  which  overlap  the  outside 
edges  of  the  steam-ports,  c and  d,  form  the  “ outside  lap  " of  the  valve ; 
and  the  parts,  1 1',  shown  in  black,  which  overlap  the  inside  edges  of  the 
steam-ports,  form  the  “ inside  lap."  Ordinarily,  in  speaking  of  a “ lap  ” of 
a valve  it  means  the  outside  lap. 

Question  180.  What  is  meant  by  the  “ lead"  of  a valve? 

Answer.  “ Lead"  means  the  width  of  the  opening  of  the  steam-port 
when  the  piston  is  at  the  beginning  of  its  stroke.  Thus,  if  the  valve,  H, 
fig.  69,  stood  in  the  position  shown,  when  the  piston  is  at  the  end  of  the 
cylinder,  and  the  piston  is  at  the  beginning  of  its  stroke,  the  opening,  a, 
of  the  steam-port,  c,  would  be  the  lead.  The  opening  of  the  port  on  the 
outside  of  the  valve  is  called  outside  lead ; on  the  inner  or  exhaust  side, 
as  shown  at  b,  it  is  called  inside  lead. 

Question  131.  What  is  meant  by  the  “travel"  of  a valve? 

Answer.  By  the  “ travel"  we  mean  the  distance  that  the  valve  is  moved 
back  and  forth,  or,  in  other  words,  its  stroke.  In  an  engine  like  that 
shown  in  Plate  III,  if  the  rocker-arms  are  both  of  the  same  length,  the 
travel  of  the  valve  will  be  equal  to  the  throw  of  the  eccentrics. 

Question  182.  What  are  the  essential  conditions  which  a slide-valve 
must  fulfil  in  governing  the  admission  and  exhaust  of  steam  to  and  from 
the  cylinder  of  an  ordinary  engine  ? 

Answer.  1.  It  must  admit  steam  to  one  end  only  of  the  cylinder  at  one 
time,  so  that  the  pressure,  which  moves  the  piston,  will  not  be  exerted  on 
both  sides  of  it  at  the  same  time. 


The  Slide-Valve. 


Fig.  68.  Slide-Valve.  Scale  in.=l  in, 


80 


Catechism  of  the  Locomotive. 


2.  It  must  cover  the  steam-ports  so  as  not  to  permit  steam  to  escape 
from  both  steam-ports  at  once. 

3.  It  must  allow  the  steam  to  escape  from  one  end  of  the  cylinder  before 
it  is  admitted  at  the  other  end,  so  as  to  give  the  steam,  which  is  to  be 
exhausted,  time  to  escape  before  the  piston  begins  its  return  stroke. 

4.  It  must  not  allow  “ live  steam  ”*  to  enter  the  exhaust-port  from  the 
steam-chest. 


5.  In  order  to  utilize  the  expansive  force  of  the  steam,  the  valve  must 
close  each  steam-port  on  the  outer  or  steam  side  before  it  is  opened  on 
the  exhaust  side. 

Question  133.  How  does  the  valve  shown  by  figs.  6j-jo  fulfil  these  con- 
ditions ff 

* By  live  steam  is  meant  steam  which  has  been  taken  direct  from  the  boiler,  and  which  has  not 
been  expanded  in  the  cylinder.  The  term  is  used  in  contradistinction  to  steam  which  has  been 
admitted  to  the  cylinder,  and  by  the  exertion  of  its  expansive  force  has  done  work  on  the  piston. 

tThe  reader  is  recommended  to  draw  a valve,  like  that  shown  in  fig.  67,  on  a card,  letting  the 
lower  edge,  a b , correspond  with  the  lower  edge  of  the  card.  This  card  can  then  be  moved  on 
the  line,  a b , and  will  show  the  action  of  the  valve  more  clearly  than  any  drawings  or  descrip- 
tion can. 


The  Slide-Valve. 


8X 


Answer.  1.  The  lap  on  the  outside  of  this  valve  being  greater  than 
that  inside,  makes  it  impossible  to  open  either  one  of  the  steam-ports  for 
the  admission  of  steam,  until  after  the  other  port  is  opened  to  the  exhaust. 
Thus  the  valve  cannot  be  moved  from  the  position  shown  in  fig.  67,  to 
that  shown  in  fig.  69,  so  as  to  open  the  port,  c,  at  a , without  first  opening 
the  port,  d,  at  b , which  allows  the  steam  in  d to  escape  into^.  The  out- 
side width  of  the  valve,  as  indicated  by  the  dotted  line,  m n , fig.  67,  is 
greater  than  the  distance  over  the  outside  edges  of  the  steam-ports — 
shown  by  the  dotted  line,  op — so  that  it  is  manifestly  impossible  for  the 
valve  to  uncover  both  steam-ports,  and  thus  admit  steam  into  each  at 
once. 

2.  The  width  of  the  exhaust  cavity,  H , in  the  valve,  measured  from  / to 
l',  is  less  than  the  distance  over  the  inner  edges  of  the  steam-ports,  c and  d 
— consequently,  these  ports  cannot  both  communicate  with  the  exhaust 
cavity  simultaneously. 

3.  If  the  valve  shown  in  fig.  69  is  moving  in  the  direction  indicated  by 
the  dart,  at  H,  it  is  obvious  that  the  steam-port,  d,  will  be  opened  to  the 
exhaust,  at  b , before  the  port,  c,  will  be  uncovered,  at  a,  for  the  admission 
of  steam.  The  same  action  will  occur  when  the  valve  moves  in  the  op- 
posite direction,  and,  as  already  pointed  out,  is  due  to  the  fact  that  the 
outside  lap  is  greater  than  that  inside. 

4.  Live  steam  cannot  enter  the  exhaust-port  unless  it  should  be  un- 
covered by  the  valve.  This  cannot  occur  unless  the  valve,  fig.  67,  should 
move  far  enough  so  that  its  edge,  a,  will  pass  beyond  the  edge,  e,  of  the 
exhaust-port.  For  this  reason  half  the  travel  of  the  valve  must  always  be 
less  than  the  widths  of  the  lap,  L,  the  steam-port,  c,  and  the  bridge,  B ,* 
added  together. 

5.  It  will  be  plain  that  if  the  valve  shown  in  fig.  69  is  moving  from  right 
to  left,  or  in  the  reverse  direction  to  that  indicated  by  the  dart,  H , that 
the  opening,  a , will  be  closed  before  the  port,  c,  is  opened  on  the  exhaust 
side,  as  the  width,  a f,  of  the  valve  is  greater  than  the  width  of  the  steam- 
port. 

Question  134.  What  other  point  must  be  observed  in  proportioning  a 
slide-valve  and  the  steam-ports  for  it? 

Answer.  The  exhaust-port  must  be  made  of  such  a width  that  when 
the  valve  is  at  the  end  of  its  travel,  the  opening  of  the  port  will  be  wide 
enough  so  as  not  to  choke  or  “ throttle ” the  exhaust  steam.  Thus,  in  fig. 
70,  the  valve  is  represented  in  the  position  it  occupies  at  one  end  of  its 


* The  metal,  B,  between  the  steam  and  exhaust-port,  is  called  a bridge. 


82 


Catechism  of  the  Locomotive. 


travel.  The  point  which  must  be  observed  is,  that  when  it  is  in  this  posi- 
tion, the  opening,  h i,  must  be  sufficiently  wide  for  the  free  escape  of 
the  exhaust  steam  from  the  port,  d into^. 

Question  135.  How  does  the  lap  of  a valve  cause  the  steam  to  act  ex- 
pansively ? 

Answer.  When  a valve  has  outside  lap,  as  was  explained  in  answer 
to  Question  102,  those  portions  of  its  face  which  cover  the  steam-ports, 
being  wider  than  the  ports,  occupy  some  time  in  moving  over  them,  during 
which  time  the  steam  is  enclosed  in  the  cylinder,  as  there  is  then  no  com- 
munication either  with  the  steam-chest  or  the  exhaust-port.  This  action 
of  the  valve  is  due  to  its  lap. 

Question  136.  What  other  good  effect  results  from  the  outside  lap  of  a 
slide-valve  ? 

Answer.  If  the  outside  lap  of  a valve  is  greater  than  that  inside — as  it 
always  is  in  well-proportioned  slide-valves — it  causes  the  exhaust-port  at 
one  end  of  the  cylinder  to  be  opened  before  the  steam-port  at  the  other 
end  is  uncovered  to  admit  steam.  This  is  shown  in  fig.  49,  from  which  it 
will  be  seen  that  if  the  valve  is  moved  in  either  direction,  one  of  the  steam- 
ports  will  always  be  opened  on  the  exhaust  side  of  the  valve  before  the 
other  one  is  opened  to  admit  steam  to  the  cylinder. 

Question  137.  What  is  the  object  in  giving  a slide-valve  lead? 

Answer.  It  is  done  so  that  the  steam-port  will  be  opened  for  the  ad- 
mission of  steam  a little  before  the  piston  reaches  the  end  of  its  stroke,  so 
that  there  will  be  a cushion  of  steam  to  receive  the  piston  and  reverse  its 
motion  at  the  end  of  the  stroke.  Another  advantage  which  lead  gives  is 
that  it  results  in  the  steam-port  being  wider  open,  for  the  admission  of 
steam  when  the  piston  begins  its  return  stroke,  than  it  would  be  if  there 
were  no  lead. 

Question  138.  What  effect  do  lap  and  lead  have  on  the  release  or  ex- 
haust of  the  steam  ? 

Answer.  They  cause  the  steam  to  be  exhausted  earlier  in  the  stroke 
than  it  would  be  if  there  were  no  lap  or  lead.  They  also  cause  the  steam- 
port  to  be  closed  on  the  exhaust  side  before  the  piston  completes  its 
stroke,  the  advantage  of  which  will  be  explained  hereafter. 

Question  139.  How  is  the  motion,  which  will  make  a slide-valve  fulfil 
the  conditions,  which  have  been  explained,  imparted  to  it  ? 

Answer.  In  the  answers  to  Questions  90,  91  and  92,  the  general  con- 
struction and  action  of  an  eccentric  was  described,  but  to  make  these  still 
plainer,  figs.  71  and  72  have  been  drawn,  showing  an  eccentric  in  two 


The  Slide-Valve. 


83 


Eccentric  and  Strap.  Scale  % in.=l  in. 


84  Catechism  of  the  Locomotive. 

> 

opposite  positions,  or  as  it  would  appear  before  and  after  the  shaft  has 
made  half  of  a revolution.*  In  fig.  71  it  is  represented  in  the  same  posi- 
tion that  it  occupies  in  fig.  30 — when  the  piston  is  at  the  beginning  of  its 
stroke,  and  the  valve  is  in  the  position  shown  in  fig.  69,  and  has  inch 
lead  at  a.  In  fig.  67  the  valve  is  shown  in  the  middle  of  the  valve-face, 
and,  as  already  explained,  in  fig.  69  it  has  moved  from  its  middle  position 
a distance  equal  to  the  lap,  £ inch,  and  lead,  inch,  or  f + T\=l^g-  inches. 
Consequently,  when  the  piston  is  at  the  beginning  of  its  stroke,  and  the 
valve  is  in  the  position  described  arid  shown  in  fig.  30,  the  eccentric  must 
be  in  a corresponding  position — that  is,  it  must  be  1TV  inches  from  the 
middle  of  its  throw.  In  figs.  71  and  72,  T'  and  T are  the  centres  of  the 
axles  or  shafts,  A B is  a vertical  centre  line  drawn  through  these  centres, 
and  n'  and  n are  the  centres  of  the  eccentrics.  The  valve,  it  will  be  seen 
from  figs.  30  and  69,  is  on  the  right  side  of  its  middle  position,  therefore, 
as  the  motion  of  the  eccentric  is  reversed  by  the  rocker,  the  centre  of  the 
eccentric  must  be  on  the  left  side  of  the  middle  of  its  throw,  as  shown  in 
fig.  71.  As  the  centre  n'  of  the  eccentric  revolves  around  T'y  the  centre 
of  the  shaft,  obviously  n'  moves  an  equal  distance  on  each  side  of  the 
vertical  line,  A B.  It  has  been  explained  in  another  place  that  the  eccen- 
trics and  their  straps,  K'  K ',  are  always  turned  so  as  to  fit  each  other 
accurately.  Consequently,  the  centre,  n' , of  the  eccentric,  always  coincides 
exactly  with  that  of  the  strap,  and,  as  the  distance  from  the  centre  n of 
the  strap,  fig.  29,  to  the  centre  of  the  pin  at  the  other  end  of  the  rod,  Z, 
always  remains  the  same,  if  we  know  the  position  of  the  centre  of  the 
eccentric,  we  can  always  know  that  of  the  pin,  which  will  show  the  move- 
ment imparted  to  the  rocker  and  by  it  to  the  valve.  Therefore,  in  study- 
ing the  action  of  an  eccentric  all  that  we  need  concern  ourselves  about  is 
the  movement  of  its  centre  in  relation  to  that  of  the  shaft. 

It  has  been  explained  that,  in  the  example  given,  the  valve,  at  the 
beginning  of  the  stroke  of  the  piston,  must  be  1^  inches  from  its  middle 
position  on  the  valve-face.  The  centre  of  the  eccentric  must  therefore  be 
the  same  distance  from  the  middle  of  its  throw.  Consequently,  if  we  draw 
a vertical  line,  a b,  fig.  71, 1T\  inches  from  A B,  the  centre  of  the  eccentric 
must  be  on  the  line,  a b,  and,  as  the  eccentric  has  4^  inches  throw,  if  we 
draw  a circle,  7i'  of,  4^-  inches  diameter,  with  T'  as  a centre,  the  centre  of 
the  eccentric  will  also  be  on  this  circle,  and  therefore  it  must  be  at  the 
point  where  the  line,  a b,  and  the  circle,  n'  of,  intersect  each  other.  As 

* Figs.  71  and  72  are  drawn  to  a scale  just  34  that  of  figs.  67  to  70 — that  is,  figs.  67  to  70  show 
the  valve  34  its  full  size,  whereas  the  eccentric  is  represented  only  34  °f  its  full  size. 


The  Slide-Valve. 


85 


a b has  two  points  of  intersection,  n'  and  o,  we  must  take  that  one  which 
will  move  the  valve  in  the  right  direction. 

QUESTION  140.  How  can  we  know  in  which  position  the  centre  of  the 
eccentric  should  be  placed? 

Answer.  This  can  easily  be  determined  if  we  know  which  way  the 
crank  is  turning  and  the  position  of  the  piston.  Thus  in  fig.  80  the  dart, 
N,  indicates  the  direction  that  the  crank  is  turning,  and  the  piston  is 
represented  at  the  front  end  of  the  cylinder.  Obviously  the  front  steam- 
port  must  then  be  opened  to  admit  steam  in  front  of  the  piston  to  force  it 
backward,  and  the  valve  must,  therefore,  be  moved  toward  the  right-hand 
side.  As  the  motion  of  the  eccentric  is  reversed  by  the  rocker,  the  centre 
of  the  eccentric  must  move  toward  the  left-hand  side.  In  fig.  71,  the 
dart,/,  shows  the  direction  of  revolution  of  the  shaft — the  same  as  A7,  in 
fig.  30.  It  will  be  evident  from  the  engraving,  fig.  71,  that  if  the  centre  of 
the  eccentric  is  located  at  n',  that  it  will  move  toward  the  left-hand  side, 
whereas  if  it  was  at  o,  it  would  move  toward  the  right-hand  side  when  the 
shaft  turns  in  the  direction  shown  by  the  arrow,/. 

Question  141.  What  does  fig.  y 2 show? 

Answer.  In  fig.  72  the  shaft  and  eccentric  are  represented  as  having 
made  a half  revolution  from  the  position  shown  in  fig.  71.  Consequently 
the  centre  n is  on  the  right-hand  side  of  the  line,  A B,  and  the  same  dis- 
tance from  it  as  it  was  in  fig.  71. 

QUESTION  142.  How  can  the  action  of  an  eccentric  be  shown  in  the  most 
simple  way  ? 

Answer.  As  explained  in  answer  to  Question  139,  the  movement  of 
the  centre  of  an  eccentric  shows  the  motion  imparted  to  the  strap  and 
rod.  All  that  is  needed,  therefore,  is  to  draw  a circle  which  will  repre- 
sent the  path  in  which  the  centre  of  the  eccentric  revolves,  and  then  lay 
out  positions  on  that  circle  that  the  centre  would  occupy  during  a whole 
revolution  of  the  crank.  But  before  describing  how  this  is  done,  it  will 
be  necessary  to  give  an  answer  to  the  following  question  : 

QUESTION  143.  How  can  the  position  of  the  crank  and  eccentric  be 
determined for  any  position  of  the  piston  ? 

Answer.  This  can  be  done  by  the  aid  of  the  diagram,  fig.  73.  Before 
describing  the  method  of  doing  this,  it  should  be  explained  first  that  the 
cross-head  and  piston,  being  rigidly  connected  together,  their  motion 
coincides  exactly.  We  may  therefore  disregard  the  piston  for  the  present, 
and  simply  observe  the  movement  of  the  pin  of  the  cross-head  in  relation 
to  the  crank.  The  large  circle  shown  by  a full  line  in  fig.  73,  represents 


The  Slide-Valve. 


87 


the  path  of  the  centre  of  the  crank-pin,  and  is  divided  into  degrees.  The 
small  circles,  0481216  20  and  24,  on  the  left-hand  side,  represent  the 
successive  positions  of  the  cross-head  pin  corresponding  to  those  shown 
in  figs.  30  to  36.  The  length  of  the  connecting-rod,  7 feet,  is  the  distance 
from  0 to  a , or  from  12  to  the  centre  T.  By  taking  this  length  in  a pair 
of  compasses,  and  with  4 as  a centre,  if  we  intersect  the  circle  with  a small 
arc  at  b,  it  will  give  the  position  of  the  crank-pin  when  the  piston  has 
moved  a distance  equal  to  that  from  0 to  4,  or  4 inches  of  the  stroke. 
With  a connecting-rod  of  the  length  given,  7 feet,  and  24  inch  stroke  of 
piston,  it  will  be  found  that  while  the  latter  has  moved  4 inches,  the  crank 
has  turned  through  45  degrees  of  a complete  revolution.  In  other  words, 
a line  b T,  drawn  through  the  centre  b of  the  crank-pin,  and  the  centre  T 
of  the  shaft,  will  form  an  angle  of  45  degrees  with  the  centre-line  a T. 
As  the  crank,  shaft,  and  eccentric  are  all  rigidly  connected  together,  if 
the  one  turns  45  degrees  of  a revolution,  the  others  must  turn  equally  as 
much.  We  will  now  draw  a circle,  nop , fig.  74,  representing  the  path  of 
the  centre  or  the  throw  of  the  eccentric,  and  its  centre  n will  be  laid  down 
in  the  position  it  occupies  when  the  piston  is  at  the  beginning  of  its  stroke, 
as  shown  in  figs.  30  and  again  in  71,  and  we  will  draw  a line,  a T,  through 
the  centre,  n,  of  the  eccentric  and  T of  the  shaft.  A similar  line  will  also 
be  drawn  in  fig.  75.  From  what  has  been  said  it  is  obvious  that  while  the 
crank  is  turning  from  the  position  shown  in  fig.  30,  to  that  shown  in  fig. 
31,  or  from  a to  b in  fig.  73=45  degrees,  that  the  eccentric  must  also  have 
turned  an  equal  amount.  Therefore,  if  from  the  line  a T,  in  fig.  75,  we 
lay  off  an  angle  a T £=45  .degrees,  the  intersection  of  the  line  b T with 
the  circle  will  represent  the  position  of  the  centre  of  the  eccentric  when 
the  piston  has  moved  4 inches,  or  is  in  the  position  shown  in  fig.  31,  and 
the  crank  is  in  the  position  shown  at  b in  fig.  73. 

Returning  again  to  fig.  73,  let  it  be  supposed  that  the  piston  has  moved 
8 inches.  We  will  take  the  centre  of  the  small  circle  8 as  a centre  and 
the  length  of  the  connecting-rod  as  a radius,  and  intersect  the  large  circle 
with  a small  arc  at  c.  It  will  then  be  found  that  in  moving  from  b to  c 
that  the  crank  has  turned  22  degrees.  Proceeding  as  before,  the  line  b T 
will  be  laid  down  in  fig.  76  in  the  same  position  as  in  fig.  75,  and  an  angle 
b T c,  equal  to  22  degrees,  will  be  laid  off  from  b T.  Then  the  intersec- 
tion of  c T with  the  circle  at  n , will  be  the  position  of  the  centre  of  the 
eccentric  when  the  piston  has  moved  8 inches  of  its  stroke. 

In  this  way  we  may  proceed  and  lay  out  the  position  of  the  eccentric 
for  each  position  of  the  piston  shown  in  figs.  30  to  37,  or  for  the  corres- 


Diagrams  showing  Movements  of  Eccentric.  Scale  % in.=l  in 


The  Slide-Valve. 


81) 

ponding  positions  of  the  crank  represented  by  a b c d e f g h i j k and  l in 
fig.  73.  This  has  been  done  in  figs.  74  to  87,  and  if  the  reader  will  draw  a 
similar  series  of  diagrams  it  will  probably  give  him  a clearer  idea  of  the 
action  of  an  eccentric  than  he  can  get  in  any  other  way.* 

Question  144.  How  can  the  movement  and  the  action  of  a valve  be 
shown  most  perfectly  on  paper  f 

Answer.  By  drawing  a diagram — that  is,  by  representing  the  valve  in 
a number  of  the  positions  it  occupies  in  relation  to  the  steam-ports  during 
a complete  stroke  of  the  piston,  and  then  drawing  what  are  called  “motion 
curves  ” through  the  inner  and  outer  edges  of  the  valve  in  each  one  of  the 
positions  in  which  it  is  represented.  As  such  curves  are  in  a sense  purely 
imaginary,  and  do  not  represent  any  object  on  an  engine,  it  is  difficult  to 
explain  clearly  their  nature  and  purpose,  and  perhaps  it  will  be  still  harder 
for  those  with  little  or  no  knowledge  of  drawing  to  understand  an  explana- 
tion, no  matter  how  clearly  it  may  be  written.  The  reader  must,  there- 
fore, expect  to  give  close  attention  and  perhaps  some  hard  study  to  the 
following  description  of  this  method  of  showing  the  movement  of  a slide- 
valve,  in  relation  to  that  of  the  piston  and  crank,  and  to  the  steam  and 
exhaust-ports : 

It  will  be  supposed,  in  the  first  place,  that  the  horizontal  line  f f,  Plate 
II,  represents  the  valve-face,  and  H a valve  with  4 inch  outside  lap  ; c and 
e are  the  steam-ports,  14  inches  wide,  and  g the  exhaust-port,  24  inches 
wide,  the  bridges  between  being  14  inches  thick.  The  valve,  H,  is  repre- 
sented in  the  position  it  would  occupy  when  the  piston  is  at  the  front  end 
of  the  cylinder,  and  at  the  beginning  of  its  stroke,  the  valve  having  T3T 
inch  lead  at  M.  BE  is  a vertical  centre  line  through  the  valve-face  and 
exhaust-port  £-/  h i is  the  vertical  centre  line  of  the  valve.  As  the  lap  is 
4 and  the  lead  the  distance,  / k , between  the  centre  line  of  the  valve 
and  that  of  the  face  must  be  | + inches.f  Let  X V represent  a 
rocker,  T , the  centre  of  the  main  shaft,  and  the  dotted  circle  around  it  the 
path  of  the  centre,  m,  of  the  eccentric,  which  has  44  inches  throw.  The 
rocker  and  eccentric,  to  save  room  in  the  engraving,  are  both  represented 
nearer  to  the  valve-face  than  they  would  be  on  an  engine.  The  position 
of  the  piston,  crank,  etc.,  are  supposed  to  be  the  same  as  shown  in  fig.  30. 
The  dart,  H,  shows  the  direction  in  which  the  valve  is  moving,  and  the 

* In  drawing  such  a series  of  diagrams,  it  will  be  best  to  make  them  to  a larger  scale  than 
they  are  represented  in  the  engravings. 

+ The  reader  is  recommended  to  use  a valve  drawn  on  card-board,  as  explained  in  the  note  to 
Question  133  in  reading  the  following  description. 


/ 


90  Catechism  of  the  Locomotive. 

one  at  in,  the  way  the  eccentric  is  revolving.  As  the  valve  should  be  1^ 
inches  from  its  central  position  at  the  beginning  of  the  stroke,  and  the 
rocker  arms  being  of  equal  length,  obviously  the  centre,  m,  of  the  eccentric 
must  also  have  moved  the  same  distance,  in  in' , from  the  vertical  line,  in' 
r',  drawn  through  the  centre  of  the  shaft.  Therefore,  if  we  draw  a verti- 
cal line,  in  t,  parallel  with  in'  r';  and  l-^g-  inches  from  it,  as  already  explained, 
its  intersection,  in,  with  the  dotted  circle  will  be  the  location  of  the  cen- 
tre of  the  eccentric,  when  the  piston  is  at  the  beginning  of  the  backward 
stroke,  and  the  valve  is  in  the  position  shown  at  H. 

It  will  now  be  supposed  that  the  piston  has  moved  4 inches,  or  into 
the  position  shown  by  fig.  31.  In  doing  so  it  will  be  seen  that  the  crank 
has  turned  a certain  distance  from  the  dead  point,  shown  in  fig.  30,  to 
the  position  represented  in  fig.  31.  It  has  been  explained  that  this  angle 
— with  a connecting-rod  and  stroke  of  piston  of  the  dimensions  given — 
will  be  45  degrees.  Therefore,  if  in  Plate  II,  we  draw  a line,  m Tr 
through  the  first  position  of  the  centre  of  the  eccentric  and  the  centre 
of  the  shaft,  and  draw  another  line,  n T,  through  T,  and  at  an  angle 
of  45  degrees  to  in  T,  its  intersection,  n,  with  the  dotted  circle  will 
represent  the  position  of  the  centre  of  the  eccentric,  when  the  piston 
has  moved  4 inches  from  the  dead  point. 

The  effect  of  this  movement  on  the  valve  can  easily  be  followed  if 
the  reader  will  observe  the  direction  of  the  motion  indicated  by  the 
darts  at  in  V X and  H.  It  will  be  noticed  that  when  the  centre  of  the 
eccentric  is  at  n , its  distance,  n n’ , from  the  vertical  centre  line  is  greater 
than  when  it  was  at  in.  The  horizontal  line,  in  in' , is  equal  to  the  dis- 
tance, j inches  between  the  centre  line  of  the  valve  and  that  of 

the  valve-face,  n n'  shows  the  distance  between  these  centre  lines  when 
the  piston  has  moved  4 inches  of  its  stroke.  If,  therefore,  we  draw  the 
valve,  with  its  centre  line,  a distance  equal  to  n n'  from  the  middle  of 
the  valve-face,  it  will  be  in  the  position  it  occupies  when  the  piston  is 
in  the  position  shown  in  fig.  31.  If  we  drew  it  in  this  position  on  the 
line,/  f,  of  Plate  II  the  drawing  would  be  liable  to  be  confused  with 
the  valve  already  represented  there.  To  avoid  such  confusion  another 
horizontal  line,  4 20',  has  been  drawn  a distance,  0 4,  equal  to  the  move- 
ment of  the  piston,  or  4 inches,  below f f,  and  on  this  line  a perpen- 
dicular, h ' i',  has  been  laid  down  at  a distance, / h' — equal  to  n n' — from 
the  centre  of  the  valve-face ; h'  i'  will  then  represent  the  middle  of  the 
valve  in  its  new  position.  The  edges  of  the  ports,  c g and  e,  have  been 
extended  downward,  and  the  lower  part  of  the  valve  has  been  drawn  on 


The  Slide-Valve. 


91 


the  line,  4 20',*  with  h'  i’  as  its  centre  line,  which  shows  it  in  the  position 
it  will  occupy  in  relation  to  the  steam  and  exhaust-ports  when  the  piston 
has  moved  4 inches  of  its  stroke,  as  shown  in  fig.  31. 

We  can  now  proceed  in  the  same  way  to  show  the  position  of  the  valve 
on  the  line,  8 16',  when  the  piston  has  moved  8 inches  of  its  stroke,  as 
represented  in  fig.  32.  It  has  been  shown  from  fig.  73  that  when  the 
cross-head  pin  has  moved  8 inches,  that  the  crank  has  turned  through 
22  degrees  of  a revolution  from  b,  or  67  degrees  from  the  dead  point,  a. 
If,  then,  we  draw  a line,  o T,  on  Plate  II,  at  an  angle  of  67  degrees  with 
m T,  its  intersection  with  the  dotted  circle  will  be  the  position  of  the 
centre  of  the  eccentric  when  the  piston  is  in  its  new  position.  The  centre 
of  the  eccentric  is  therefore  a distance,  o o',  from  the  centre  line,  m'  r', 
which  indicates  the  movement  of  the  valve.  For  the  reason  already  ex- 
plained— that  is,  to  avoid  confusion  in  the  diagram,  the  valve  will  be 
represented  in  its  third  position  on  the  line,  8 16',  and  it  will  be  laid  off 
as  before. 

Proceeding  in  the  same  way,  the  positions,  ft  q r and  s,  of  the  centre 
of  the  eccentric,  when  the  piston  has  moved  12,  16,  20  and  24  inches  of 
its  stroke,  may  be  laid  down  in  Plate  II.  The  edges  of  the  steam  and 
exhaust-ports  and  the  centre-line,^  E,  are  extended  downward,  and  the 
distance,  C E,  is  made  equal  to  the  stroke  of  the  piston.  Horizontal 
lines,  8 16',  12  12',  16  8',  etc.,  are  drawn  at  distances  from  f f equal  to  the 
movement  of  the  piston.  The  different  positions  of  the  valve  indicated 
in  figs.  30  to  36  are  then  laid  down  on  these  lines. 

We  now  have  a graphical  representation  of  the  movement  of  the  valve 
in  seven  successive  positions  of  a stroke.  The  position  of  the  outer  edge 
of  the  valve,  which  controls  the  admission  of  steam,  is  shown,  in  its  rela- 
tion to  the  port,  <?,  at  M N O P Q R and  S,  and  the  inner  edge  which 
controls  the  exhaust  is  shown  at  M'  N'  O'  P'  Q R'  and  S'.  It  will  be 
seen  that  at  Wthe  steam-port  is  wide  open,  and  remains  so  until  the  valve 
gets  into  the  position  shown  at  P,  when  it  begins  to  close  the  port.  At 
R it  is  almost  entirely  closed.  If  now  we  draw  a curve,  M N O P Q R S, 
through  the  edge  of  the  valve  in  its  successive  positions,  that  curve  will 
show  the  movement  of  the  valve  in  relation  to  the  steam-port  during  the 
whole  stroke.  Horizontal  lines  1 23',  2 22',  3 21',  etc.,  have  been  drawn 
between  f f and  4 20'  to  represent  each  inch  of  the  stroke,  and  the  spaces 
between  these  lines  have  been  subdivided  by  other  lines  which  represent 

* To  avoid  too  much  confusion,  in  the  diagram  only  the  edges  of  the  valve,  which  control  the 
admission  and  exhaust  of  steam,  are  represented  in  its  successive  positions. 


92 


Catechism  of  the  Locomotive. 


eighths  of  an  inch,  and  the  whole  distance  from  C to  E has  been  sub- 
divided in  the  same  way.  The  relation  of  the  curve,  M N O-S,  to  these 
horizontal  lines  will  show  exactly  the  position  of  the  outer  or  steam  ad- 
mission edge,  M,  of  the  valve  at  all  points  of  the  stroke  of  the  piston.  Thus, 
the  distance  of  the  curve  on  the  line  1 23'  from  the  outer  edge  of  the  port, 
c , as  indicated  by  the  line  at  w,  shows  how  wide  the  port  was  open  when 
the  piston  had  moved  1 inch  of  its  stroke.  A similar  line  at  x shows  the 
width  of  opening  at  14  inches  of  the  stroke,  and  the  intersection  of  the 
curve  with  the  outer  edge  of  the  port  at  20f  inch  of  the  stroke  shows  that 
the  port  was  then  closed  and  the  steam  cut  off. 

A similar  curve,  M'  N’  O'  P'  Q R'  S',  shows  the  position  of  the  inner 
or  exhaust  edge,  M’ , of  the  valve  in  relation  to  the  port,  e.  Other  curves, 
S U M,  and  S'  U’  M ',  have  also  been  drawn  which  represent  the  move- 
ment of  the  valve  during  the  return  stroke  of  the  piston.  The  dotted  line, 
below  R’ , shows  the  width  of  the  opening  of  the  port,  e,  to  the  exhaust 
when  the  piston  has  moved  20^  inches,  and  the  intersection  at y shows  that 
the  port  was  closed  to  the  exhaust  at  22T7¥  inches  of  the  stroke. 

The  slight  intersection  of  the  curve,  5 U M,  with  the  outer  edge  of  the 
port,  c , just  below  M,  shows  that  the  port  was  slightly  opened  before  the 
piston  had  reached  the  end  of  its  stroke,  and  the  intersection  at  z shows 
that  the  port,  e , was  open  to  the  exhaust  when  the  piston  still  had  to  move 
1 inch  to  complete  its  stroke. 

It  will  thus  be  seen  that  such  diagrams  show  very  plainly  the  movement 
of  a valve,  and  they  present  to  the  eye  a diagram  which  shows  its  different 
positions  during  a whole  revolution  of  the  crank.  A clearer  idea  may 
thus  be  formed  of  its  action  than  it  would  be  possible  to  have  without 
some  such  a graphical  representation. 

QUESTION  145.  Can  the  drawing  of  such  a diagram  be  simplified  in 
any  way  ? 

Answer.  Yes,  if  it  is  observed  that  the  only  way  in  which  the  rocker 
effects  the  movement  of  the  eccentric  and  valve  is  to  reverse  their  motions 
in  relation  to  each  other.  We  may,  for  simplicity,  suppose  the  rocker  is 
removed  and  that  the  shaft  and  eccentric  are  located  at  T'  above  T and 
opposite  to  the  valve,  and  that  the  eccentric  is  connected  by  a rod,  m"  D, 
directly  with  the  valve.  In  that  case,  in  order  to  move  the  valve  in  the 
same  direction  that  it  was  moved  with  the  rocker,  it  will  be  essential  that 
the  centre,  m" , of  the  eccentric  be  in  the  opposite  position  in  its  path  from 
that  in  which  it  is  shown  at  m below.  This  will  be  plain  if  the  reader  will 
follow  the  motions  indicated  by  the  darts  at  m V X and  H,  and  then 


The  Slide-Valve. 


93 


observe  the  direction  that  m"  and  the  valve,  H,  are  supposed  to  be  mov- 
ing. It  should  be  observed  that  the  centre,  m" , must  be  on  the  right  side 
of  the  centre  line,  T'  T,  instead  of  the  left,  and  that  the  distance,  m!"  in" , 
from  the  centre  line  must  be  the  same  as  m in'  equal  to  j k or  1^  inches. 

On  the  middle  of  C K,  the  vertical  centre  line  of  the  valve-face,  we  will 
now  take  A as  a centre,  and  draw  a circle,  C'  F E D,  to  represent  the 
path  of  the  centre  of  the  crank-pin.  It  will  also  be  imagined  that  the 
centre,  T,  of  the  shaft  is  located  at  A,  and  that  the  circle,  m" " n"-s" , re- 
presents the  path  of  the  centre  of.  the  eccentric,  and  that  its  centre,  m" ", 
occupies  the  same  relation  to  the  vertical  centre  line,  C E,  that  in"  does  to 
T'  T — that  is,  it  is  1^  inches  to  the  right  of  C E.  If  now  we  draw  a 
vertical  line,  m" " i,  through  the  centre,  in" ",  of  the  eccentric  upward  it 
will  coincide  with  i h,  the  centre  line  of  the  valve.  By  drawing  a line,  A 
in"  " u,  through  the  centre,  in"",  of  the  eccentric  to  the  circumference  of 
the  large  circle,  which  represents  the  path  of  the  centre  of  the  crank-pin, 
and  then  from  u,  the  intersection  of  this  line  with  the  large  circle,  laying 
off  a space,  u v,  equal  to  45  degrees,  and  drawing  a line,  v A,  its  intersec- 
tion at  n"  with  the  path  of  the  centre  of  the  eccentric  will  give  the  posi- 
tion of  its  centre  when  the  piston  has  moved  4 inches.  The  successive  po- 
sitions, o"  p"  q",  etc.,  of  the  curve  of  the  eccentric  can  then  be  laid  out  in 
the  way  described,  and  by  drawing  perpendicular  lines  through  these  cen- 
tres they  will  give  the  corresponding  positions  of  the  middle  of  the  valve. 

QUESTION  146.  What  is  the  effect  of  increasing  the  lap  of  a valve  if 
Ihe  travel  remains  the  same? 

Answer.  It  shortens  the  period  for  the  admission  of  steam — that  is,  it 
cuts  the  steam  off  earlier  in  the  stroke.  It  also  closes  and  opens  the  ports 
to  the  exhaust  earlier.  Thus,  in  fig.  88,  motion  curves  have  been  drawn 
for  a valve  with  1£  inch  lap  and  4£  inch  travel.  From  the  steam  curve, 
M N-S,  it  will  be  seen  that  the  steam-port  is  closed  at  q,  or  at  16^  inches 
of  the  stroke  instead  of  20£,  as  it  is  when  the  valve  has  $•  inch  lap,  as 
shown  in  Plate  II.  The  exhaust  curve,  M'  N'-S' , shows  that  the  port,  e , 
is  closed  on  the  exhaust  side  at  21£  inches  instead  of  22f  inches,  and  that 
on  the  return  stroke  it  opens  the  port  to  the  exhaust  at  21f  inches  instead 
of  23,  as  shown  in  Plate  II. 

It  will  also  be  seen  that  with  the  proportions  of  the  valve  and  the  travel 
represented  in  fig.  88,  that  the  steam-port,  c,  is  not  opened  wide  at  any 
period  of  the  stroke. 

QUESTION  147.  If  the  lap  remains  the  same,  what  is  the  effect  of 
reducing  the  travel? 


94  Catechism  of  the  Locomotive. 

Answer.  1.  Whenever  the  travel  is  less  than  twice  the  lap  added  to 
twice  the  width  of  one  of  the  steam-ports,  the  latter  will  not  be  opened 
wide.  This  is  shown  in  fig.  88,  in  which  the  valve  has  inches  lap  and 
the  steam-port  is  1£  wide,  so  that  li  + ljx  2=5  inches.  As  the  travel  is 
only  4£,  the  valve  does  not  move  far  enough  to  uncover  the  steam-port 
completely.  It  is  also  shown  in  fig.  89  with  a valve  having  inch  lap  and 
a travel  of  3| — represented  by  the  motion  curves  drawn  in  full  lines.  It 
will  be  seen  at  w'  that  the  greatest  width  of  opening  of  the  port  is  only  \ 
inch.  The  dotted  curves  show  the  motion  of  the  valve  with  2f  inches 
travel.  They  show  at  w that  the  maximum  opening  of  steam-port  is  only 
i inch. 

2.  The  period  of  admission  is  reduced  or  the  steam  is  cut  off  shorter. 
At  q and  q',  in  fig,  89,  the  motion  curves  show  that  with  inch  lap  and 
3^  and  2f  inches  travel,  the  valve  closes  the  steam-port  at  13J  and  17J 
inches  of  the  stroke  instead  of  20J  inches  with  4£  inches  travel,  as  shown 
in  Plate  II. 

3.  The  steam-port  is  closed  and  opened  to  the  exhaust  earlier.  Thus,  at 
y and_y',  fig.  89,  the  curves  show  that  the  steam-port,  e,  is  closed  at  19f  and 
21^  inches  of  the  stroke  instead  of  22^,  as  shown  in  Plate  II,  with  4-J-  inches 
travel.  At  z and  z'  the  curves  show  that  the  port  is  opened  on  the  ex- 
haust side  at  21f  and  19f  inches  of  the  stroke  instead  of  23  inches. 

4.  The  valve  opens  the  steam-port  for  the  admission  of  steam  earlier 
with  a short  travel  than  with  a long  one.  This  is  indicated  by  the  two 
curves  just  below  M,  fig.  89.  The  full  line  shows  that  the  port  is  opened 
when  the  piston  still  has  inch  to  move  before  completing  its  stroke’. 
The  dotted  curve,  which  shows  the  movement  of  the  valve  with  a 
shorter  travel,  indicates  that  the  valve  opens  the  port,  while  the  piston 
still  has  T\  inch  to  move  before  it  reaches  the  end  of  its  stroke. 

Question  148.  What  occurs  when  the  valve  closes  communication  be- 
tween the  exhaust-port  and  the  steam-port  ahead  of  the  piston  ? 

Answer.  The  steam  which  has  not  been  exhausted  from  the  cylinder 
is  enclosed  in  it  and  is  compressed  by  the  advancing  piston,  and  it  thus 
acts  like  the  pre-admission  of  steam  before  the  piston  has  completed  its 
stroke — that  is,  as  a cushion  to  resist  the  momentum  of  the  piston  and 
bring  it  to  a state  of  rest  at  the  end  of  the  stroke. 

Question  149.  Does  this  compression  residt  in  loss  of  energy  ? 

Answer.  No,  because  the  power  required  to  compress  the  confined 
steam  is  again  given  out  by  its  expansion  behind  the  piston  on  its  return 
stroke.  In  fact,  it  results,  as  explained  in  answer  to  Question  125,  in  a 


The  Slide-Valve. 


97 


direct  economy,  because  by  the  compression  of  confined  steam  the  clear- 
ance spaces  and  steam-ways  are  filled  with  steam  of  a high  pressure. 
Without  such  compression  it  would  be  necessary  to  fill  them  with  live 
steam  when  the  steam-port  is  opened. 

If  the  steam  thus  compressed  is  exhausted  before  it  is  expanded  to  the 
pressure  it  had  before  compression,  there  is  a loss  due  to  the  escape  of 
steam  at  this  higher  pressure. 

Question  150.  What  is  the  effect  of  inside  lap? 

Answer.  It  delays  the  release  or  exhaust  of  steam  and  increases  the 
compression.  For  this  reason  no  inside  lap  is  usually  given  to  valves 
for  engines  which  ran  at  a high  rate  of  speed,  as  with  it  the  exhaust 
steam  has  not  time  enough  to  escape  freely.  In  fact,  in  some  cases  what 
is  called  inside  clearance  is  given  to  valves — that  is,  the  width  of  the 
exhaust  cavity  of  the  valve  is  made  somewhat  wider  than  the  distance 
over  the  inner  edges  of  the  steam-ports,  so  that  it  does  not  entirely  cover 
them  when  it  is  in  the  middle  of  the  valve-face.  The  effect  of  inside  clear- 
ance is  just  the  reverse  of  that  produced  by  inside  lap — that  is,  it  causes 
the  release  to  occur  earlier  in  the  stroke  and  compression  later. 


CHAPTER  IX. 


THE  ACTION  OF  THE  PISTON,  CONNECTING-ROD  AND  CRANK.* 

QUESTION  151.  What  effect  does  the  connecting-rod  have  on  the  relative 
movements  of  the  piston  and  crank  ? 

Answer.  The  inclination  of  the  rod  to  the  centre  line,  A B C,  of  the 
cylinder,  as  shown  by  E F,  in  fig.  90,  causes  the  piston  to  move  some- 
what more  than  half  its  stroke  while  the  crank  is  passing  from  the  dead- 
point,  B to  F,  or  during  the  first  quarter  of  its  revolution,  and  somewhat 
less  than  half  its  stroke  during  the  second  and  third  quarter,  and  again 
somewhat  more  during  the  last  quarter  of  the  revolution,  or  while  the 
crank-pin  is  passing  from  G to  B. 

Question  152.  How  can  this  effect  of  the  inclination — or  “angularity 
as  it  is  called — of  the  connecting-rod  be  shown  ? 

Answer.  It  will  be  made  apparent  if  we  draw  a circle,  B F C G,  fig. 
90,  representing  the  path  of  the  centre  of  the  crank-pin,  and  then  divide 
it  into  16  equal  parts,  1 2,  2 3,  3 4,  etc.  From  1,  which  is  the  front  dead- 
point  of  the  crank,  a distance  1 V will  be  laid  off  equal  to  the  length  from 
centre  to  centre  of  the  journals  of  the  connecting-rod,  and  from  9,  the 
back  dead-point  of  the  crank,  a distance  of  9 9'  is  laid  off  also  equal  to  the 
length  of  the  connecting-rod  ; 1'  and  9'  then  represent  the  positions  of  the 
centre  of  the  cross-head  pin  when  the  crank  is  at  its  dead-points  and  when 
the  piston  is  at  the  ends  of  its  stroke.  As  explained  before,  the  cross-head 
and  the  piston  are  rigidly  connected  together,  so  that  the  motion  of  the 
one  represents  that  of  the  other.  The  movement  of  the  centre  of  the 
cross-head  pin  may  therefore  be  regarded  as  the  same  as  that  of  the  pis- 
ton. If  now,  with  a pair  of  compasses,  we  take  a distance  equal  to  V 1,  or 
the  length  of  the  connecting-rod,  and  from  5 as  a centre  a short  arc,  E,  is 
described  so  as  to  intersect  the  centre-line,  A 9'  B C,  the  point  of  inter- 
section will  represent  the  position  of  the  centre  of  the  cross-head  pin  when 
the  crank  is  at  5,  or  when  it  has  turned  £ of  a whole  revolution.  If  we 
subdivide  the  distance,  1'  9',  which  represents  the  stroke  of  the  piston,  in- 
to two  equal  parts,  1'  a and  a 9',  then  it  will  be  found  that  the  distance 

* This  chapter  should  be  read  in  connection  with  Chapters  I and  II. 


Piston,  Connecting-Rod  and  Crank. 


99 


from  1'  to  E is  somewhat  more  than  V a , or  half  the  stroke  of  the  piston. 
That  is,  while  the  crank-pin  has  moved  from  1 to  5,  or  turned  £ of  a revo- 
lution, the  piston  has  traveled  a little  more  than  half  its  stroke,  When  the 


crank-pin  reaches  the  dead-point  at  9,  then  the  cross-head  pin  will  be  at 
9',  so  that  while  the  crank  has  moved  through  the  second  quarter  of  its 


100 


Catechism  of  the  Locomotive. 


revolution  the  cross-head  pin  and  piston  have  traveled  a distance,  E 9', 
somewhat  less  than  half  the  stroke,  a 9'. 

Again,  when  the  crank  has  reached  13,  and  has  passed  through  the 
third  quarter  of  its  revolution,  if  we  take  the  length  of  the  connecting- 
rod,  and  from  13  as  a centre,  with  13  A'  as  a radius,  describe  another  short 
arc,  it  will  intersect  A B again  at  E,  so  that  while  the  crank-pin  has  re- 
volved through  the  third  quarter  the  piston  has  moved  from  9'  to  E,  or 
less  than  half  its  stroke.  When  the  crank  again  reaches  1 the  cross-head 
pin  will  be  at  V,  so  that  it  and  the  piston  have  moved  more  than  half  a 
stroke  while  the  crank  passed  from  13  to  1,  the  fourth  quarter  of  its 
revolution.  Owing  to  this  action  of  the  connecting-rod  which  is  due  to 
its  angularity , as  it  is  called,  the  crank-pin  is  behind  the  piston  during  its 
backward  stroke  and  ahead  of  it  during  the  forward  stroke. 

Question  153.  How  does  the  action  of  the  connecting-rod  influence  the 
motion  of  the  piston  and  valve  in  relation  to  each  other  ? 

Answer.  As  the  crank  moves  slower  than  the  piston  during  the  first 
and  last  quarter  of  the  revolution,  and  as  the  valve  is  moved  by  the  eccen- 
tric, and  it  in  turn  by  the  shaft  and  crank,  consequently  the  movement  of 
the  valve  is  delayed  in  relation  to  that  of  the  piston  during  these  periods. 
As  the  crank  moves  faster  than  the  piston  during  the  second  and  third 
quarters,  the  points  of  cut-off  and  release  occur  earlier  in  the  stroke  dur- 
ing these  periods  than  they  do  during  the  first  and  fourth  quarters  of  the 
crank’s  revolution. 

This  is  not,  however,  a matter  of  very  great  practical  importance  with 
stationary  engines  which  run  at  comparatively  slow  speeds ; but  if  it  is 
thought  desirable,  the  period  of  admission  and  the  point  of  release  for 
both  stokes  can  be  equalized,  either  by  giving  the  valve  more  lead  or  lap 
at  one  end  than  the  other,  or  by  making  the  one  steam-port  wider  than 
the  other.  The  mechanism  employed  for  moving  locomotive  slide-valves, 
however,  furnishes  us  with  the  means  of  modifying  their  motion  in  rela- 
tion to  that  of  the  piston,  and  of  thus  equalizing  the  periods  of  admission 
and  release  for  the  front  and  back  strokes.  The  methods  of  doing  this 
will  be  more  fully  explained  hereafter. 

Question  154.  What  effect  does  the  angularity  of  the  connecting-rod 
have  on  the  cross-head  and  slides  ? 

Answer.  When  the  crank  is  revolving  in  the  direction  represented  by 
the  dart,  F,  in  fig.  90,  the  piston  pushes  the  connecting-rod  and  it  is  then 
plainly  subjected  to  a compressive  strain  while  the  piston  is  moving  back- 
ward or  toward  the  shaft,  and  during  the  first  hatf  of  the  revolution  of 


Piston,  Connecting-Rod  and  Crank. 


101 


the  crank,  The  pressure  on  the  cross-head  and  guides  due  to  the  angle 
of  the  rod  is  therefore  upward.  When  the  piston  is  moving  from  the 
shaft,  or  making  its  forward  stroke,  and  the  err  ;k  is  passing  from  C 
to  B,  the  piston  then  pulls  the  connecting-rod,  and  it  is  then  in  ten- 
sion, and  the  pressure  on  the  cross-head  and  guides  is  again  upward.  If, 
however,  the  crank  should  revolve  in  the  opposite  direction  from  that 
represented  by  the  dart,  the  pressure  on  the  cross-head  and  guides  would 
be  downward — that  is,  the  direction  of  the  pressure  on  the  guides  is  re- 
versed, when  the  direction  of  the  revolution  of  the  crank  is  reversed,  or 
when  the  engine  runs  backward. 

QUESTION  155.  What  is  the  nature  of  the  motion  of  a piston  of  a stea?n- 
engine  during  each  stroke  ? 

Answer.  When  it  is  at  the  end  of  the  cylinder,  and  the  crank  is  at  one 
of  the  dead-points,  the  piston  is  momentarily  at  rest  or  stationary.  After 
it  starts  its  speed  is  increased  up  to  a point  near  the  middle  of  the  stroke, 
where  it  reaches  its  maximum  velocity.  From  that  point  the  speed  is  di- 
minished to  the  end  of  the  stroke,  when  it  again  comes  to  a momentary 
state  of  rest  before  beginning  the  return  stroke.  During  the  return  stroke 
its  motion  is  almost  exactly  the  same,  excepting  that  the  direction  of  its 
movement  is  reversed. 

Question  156.  How  can  the  motion  of  the  piston  be  represented  graphi- 
cally ? 

Answer.  This  can  be  done  by  constructing  a diagram  as  shown  in  fig. 
90.  In  this  the  circle,  B C,  as  already  explained,  represents  the  path  in 
which  the  centre  of  the  crank-pin  revolves  and  is  divided  into  sixteen 
equal  parts,  1 2,  2 3,  3 4,  etc.  Let  it  be  supposed  that  the  crank  is  turn- 
ing in  the  direction  indicated  by  the  arrow,  F — which  is  the  way  a locomo- 
tive driving-wheel  would  move  in  running  forward.  If  the  crank  is  re- 
volving at  a uniform  speed  the  crank-pin  will  move  through  each  of  the 
spaces  1 2,  2 3,  3 4,  etc.,  in  equal  times.  If  we  take  a pair  of  compasses,  with 
a distance  between  the  points  equal  to  the  length  of  the  connecting-rod, 
and  then  with  2 as  a centre  we  describe  a small  arc  to  intersect  the  centre 
line,  A B , at  2',  the  point  of  intersection  will  be  the  position  of  the  centre 
•of  the  cross-head  pin  when  the  crank-pin  is  at  2.  The  distance  from  V to 
2'  will  then  represent  the  movement  of  the  cross-head  and  piston  while 
the  crank-pin  was  passing  from  1 to  2.  If  we  place  the  point  of  the  com- 
passes at  3 and  describe  another  arc,  3',  intersecting  the  centre  line,  A B, 
then  the  distance,  2'  3',  will  be  that  which  the  cross-head  has  moved  while 
the  crank-pin  was  passing  from  2 to  3.  If,  in  a similar  way,  we  draw  sue- 


102 


Catechism  of  the  Locomotive. 


cessive  arcs,  4'  5'  6',  etc.,  from  4 5 6,  etc.,  as  centres,  then  the  Spaces,  3'  4', 
4'  5',  5'  6',  etc.,  will  represent  the  movement  of  the  cross-head  and  piston 
while  the  crank-pin  is  passing  over  the  successive  spaces  laid  out  in  the 
circle,  B C.  An  inspection  of  the  spaces  V 2',  2'  3',  3'  4',  etc.,  will  show 


that  they  successively  increase  from  the  beginning  to  near  the  middle  of 
the  stroke  of  the  piston,  and  they  then  diminish  from  near  the  middle  to 
the  end  of  the  stroke.  The  movement  of  the  piston  during  its  forward 


Piston,  Connecting-Rod  and  Crank. 


103 


stroke  is  the  same  as  that  represented  in  the  diagram,  but  in  a reversed 
direction. 

Question  157.  How  can  the  velocity  of  the  piston  during  any  portion 
of  its  stroke  be  ascertained  ? 

Answer.  In  explaining  this,  it  will  first  be  assumed  that  the  stroke  of 
the  piston  is  2 feet,  and  that  the  crank  is  moving  in  its  path,  B C,  at  a 
velocity  of  30  feet  per  second. 

It  should  be  noticed  that  a point  like  the  centre  of  a crank-pin  which  is 
moving  in  a circle  is  constantly  changing  the  direction  of  its  motion.  At 
any  one  instant  of  time,  however,  it  moves  at  right  angles  to  the  centre 
line  of  the  crank.  Thus,  when  the  crank,  F S,  fig.  91,  is  in  the  position 
shown,  the  line,  a F,  drawn  at  right  angles  to  F S represents  the  instan- 
taneous direction  in  which  F is  moving  when  in  the  position  represented. 
If  the  length  of  a F represents  the  velocity =30  feet  per  second — of  the 
crank-pin,  then  by  the  principles  of  the  composition  of  motion,  if  this  line 
is  made  the  diagonal  of  a parallelogram,  a b F d,  of  which  the  two  sides, 
a b and  d F,  are  horizontal  and  a d and  b F vertical,  then  these  sides  will 
represent  the  horizontal  and  vertical  velocity  of  the  centre  of  the  crank- 
pin.  As  the  horizontal  movement  of  the  crank-pin  is  nearly  coincident 
with  that  of  the  cross-head  and  piston,  the  motion  of  these  latter  parts 
being  communicated  to  the  crank-pin  by  the  connecting-rod,  therefore 
the  line,  d F or  a b,  which  represents  the  horizontal  velocity  of  the  crank- 
pin,  will  also  represent  very  nearly  the  velocity  of  the  cross-head  and 
piston.  Similar  diagrams  for  other  positions  of  the  crank  are  given  in 
figs.  92  and  93,  in  which  the  horizontal  lines,  d F,  represent  approximately 
the  horizontal  velocity  of  the  crank-pin  and  piston. 

QUESTION  158.  What  effect  has  the  connecting-rod  on  the  velocity  of 
the  piston  ? 

Answer.  As  already  explained,  the  velocity  of  the  piston  is  accelerated 
by  the  connecting-rod  while  the  former  is  moving  from  the  front  end  of 
the  cylinder  to  the  middle  of  the  stroke,  and  again  when  it  moves  from 
the  middle  to  the  front  end.  It  is  correspondingly  retarded  at  the  other 
end  of  the  cylinder. 

QUESTION  159.  Do  the  diagrams  in  figs,  gi,  92,  and  qj  represent  the 
velocity  of  the  piston  precisely  ? 

Answer.  No ; they  do  not  show  the  effect  of  the  angularity  of  the 
connecting-rod. 

Question  160.  How  can  a diagram  be  drawn  which  will  show  the 
velocity  of  the  piston  correctly  ? 


104 


Catechism  of  the  Locomotive. 


Answer.  This  can  be  done  if  the  line,  a F,  figs,  91.  92,  and  93,  which 
represents  the  circumferential  velocity  of  the  crank-pin  is  made  equal  to 
the  radius,  F S,  of  the  crank.  Then  if  the  line,  E F,  which  represents 
the  centre  line  of  the  connecting-rod  is  prolonged  so  as  to  intersect  the 
vertical  line,  G H,  drawn  through  the  centre  of  the  shaft,  S,  at  g,  then 
the  line,^  S,  will  represent  correctly  the  velocity  of  the  piston.  If  the 
crank-pin  is  in  a position  on  the  right  side  of  G H,  then  the  distance  of  g, 
the  point  of  intersection  of  E F with  the  vertical  line  from  the  centre,  S, 
of  the  shaft  will  represent  the  velocity  of  the  piston.* 

Question  161.  How  can  the  velocity  of  the  piston  be  shown  during  its 
whole  stroke  ? 

Answer.  It  has  been  explained  how  the  velocity  at  any  one  point  may 
be  ascertained.  We  may  determine  the  velocity  for  each  of  a number  of 
successive  points  of  the  stroke,  and  then  construct  a diagram  which  will 
represent  graphically  the  rate  of  speed  or  velocity  of  the  piston  during 
the  whole  stroke  of  the  piston  or  revolution  of  the  crank.  Thus,  fig.  91 
represents  the  crank  in  the  position  marked  2,  in  fig.  90.  The  centre  line, 
E F,  of  the  connecting-rod  is  extended  to  g,  so  that  g S represents  the 
velocity  of  the  piston  at  the  instant  that  the  crank-pin  is  at  2,  fig.  90. 
A perpendicular  line,  2'  h , equal  to  Sg,  of  fig.  91,  is  then  drawn,  in  fig.  90, 
from  2',  the  position  of  the  cross-head  pin  corresponding  to  that  of  the 
crank  at  F,  in  fig.  91.  In  fig.  92,  the  crank-pin,  F,  is  in  the  position  3,  of 
fig.  90.  The  centre  line,  E F,  of  the  connecting-rod  is  again  extended  to 
g,  and  the  distance,  Sg,  is  laid  off  from  3',  in  fig.  90 — which  is  the  corres- 
ponding position  of  the  cross-head  pin — to  i.  In  the  same  way  the 
velocity  of  the  cross-head  pin  is  plotted  for  each  of  its  positions,  4',  5',  6', 
7'  and  8',  and  a curve,  A h ij  k l in  n 9',  fig.  90,  is  drawn  through  the 
extremities  of  the  perpendicular  lines.  The  perpendicular  distance  of  this 
curve  below  the  centre  line,  A 9',  represents  the  velocity  of  the  cross-head 
pin  and  piston  for  each  point  of  the  backward  stroke.  A similar  curve 
has  been  drawn  above  the  line  A B,  and  shows  the  velocity  of  the  piston 
during  the  forward  stroke. 

QUESTION  162.  What  is  shown  by  the  form  of  these  curves? 

Answer.  It  will  be  seen  from  the  engraving  that  the  curves  do 
not  form  a true  circle,  but  the  figure  is  somewhat  egg-shaped — 


* The  demonstration  of  this  theorem  would  require  the  introduction  of  mathematical  princi  • 
pies  which  would  be  out  of  place  in  an  elementary  book  like  this.  The  reader  will  find  the 
whole  subject  very  fully  discussed  in  “ A Practical  Treatise  on  the  Steam-Engine,”  by  Arthur 
Rigg,  and  in  George  C.  V.  Holmes’s  excellent  little  book  on  the  Steam-Engine. 


Piston,  Connecting-Rod  and  Crank. 


105 


that  is,  the  left-hand  or  front  portion  of  each  of  them  is  fuller  than 
at  the  other  end,  showing,  as  has  already  been  pointed  out,  that  the 


Fig-.  94.  Diagram  showing  Velocity  of  Piston.  Scale  ^ in.-=l  ft. 

velocity  of  the  piston,  owing  to  the' influence  of  the  angularity  of  the  con- 
necting-rod, is  somewhat  greater  during  the  first  and  last  quarters  of  the 
revolution  than  it  is  during  the  second  and  third. 


106 


Catechism  of  the  Locomotive. 


Question  163.  Is  any  considerable  amount  of  power  required  to  acceler- 
ate the  piston  and  other  reciprocating  parts  of  an  engine  during  the  first 
half  of  the  stroke  ? 

Answer.  Yes.  In  fast-running  engines  much  more  power  is  required 
to  accelerate  the  reciprocating  parts  during  the  first  half  of  each  stroke 
than  is  usually  supposed. 

Question  164.  How  can  this  be  shown? 

Answer.  This  will  be  apparent  if  we  will  compare  the  velocity  of  these 
parts  with  those  of  a falling  body.  To  do  this,  it  will  be  supposed  that 
the  cylinder  of  the  engine  is  placed  vertically  above  the  crank,  as  shown 
in  fig.  94,  and  that  the  cross-head  starts  from  A.  The  curve  A h ij  k l m 
n o shows  the  velocity  of  the  piston  when  the  crank-pin  is  moving  with  a 
circumferential  velocity  of  30  feet  per  second,  which  is  equivalent  to  a 
speed  of  about  50  miles  per  hour  for  a locomotive  having  driving-wheels 
5 feet  in  diameter  and  2 feet  stroke  of  piston.  Another  curve,  A h'  i' j'  k'  l' m' 
n,  has  been  constructed  to  show  the  velocity  which  a body  falling  freely 
from  A,  would  acquire  in  a distance,  A o,  equal  to  the  stroke  of  the  piston. 
It  should  be  observed  that  the  horizontal  distance  of  the  two  curves  from 
the  vertical  line,  A o,  represents  the  velocities  of  the  piston  and  of  the 
falling  body.  They  can  therefore  be  compared  with  each  other,  and  it 
will  be  seen  that  at  the  middle  of  the  stroke  of  the  piston  its  velocity  is 
about  four  times  that  of  the  falling  body.  It  must  be  remembered,  as  was 
explained  in  Chapter  I,  that  the  force  which  moves  and  gives  velocity  to 
a falling  body  is  its  own  weight,  or  the  attraction  of  gravitation,  and  that 
the  velocity  which  a body  acquires  is  proportional  to  the  force  acting  on 
it.  If,  then,  the  reciprocating  parts  of  an  engine  in  moving  a given  dis- 
tance have  a velocity  imparted  to  them  four  times  as  great  as  that  which 
a falling  body  would  acquire  in  the  same  distance,  the  force  which  acts  on 
the  reciprocating  parts  to  produce  this  motion  must  be  equal  to  over  four 
times  their  own  weight.  As  these  parts  of  a passenger  locomptive,  with 
18  x 24-inch  cylinders,  weigh  about  550  lbs.,  the  pressure  on  the  pistons 
required  to  give  them  the  required  velocity  in  moving  from  the  beginniug 
to  the  middle  of  the  stroke  at  a speed  of  50  miles  an  hour,  must  be  equal 
to  that  produced  by  a weight  of  not  less  than  550x4=2,200  lbs.  acting 
through  a distance  of  1 foot. 

QUESTION  165.  Is  the  rate  of  the  acceleration  of  the  velocity  of  a piston 
the  same  as  that  of  a falling  body  ? 

Answer.  No.  A falling  body  can  move  freely  under  the  action  of  the 
force  which  attracts  or  impels  it  downward,  whereas  the  movement  of  the 


Piston,  Connecting-Rod  and  Crank.  107 

reciprocating  parts  of  a steam-engine  are  restrained  by  the  crank,  which 
moves  in  its  path  at  a nearly  uniform  rate  of  speed.  The  relative  velocity 
of  a piston  and  a falling  body  are  shown  by  the  form  of  the  curves,  A h ij 
k l m n o and  A h'  i'  j'  k'  l'  in'  n'  o,  in  fig.  94,  from  which  it  will  be  seen 
that  in  moving  from  A to  h and  i the  rate  of  acceleration,  or  the  increase 
in  the  speed  of  the  piston  is  very  great,  whereas  from  / to  j,  and  j to  k , it 
is  very  slight,  and  the  motion  begins  to  be  retarded  at  k.  A falling  body, 
as  was  explained  in  answer  to  Questions  13  to  20,  has  a uniform  increase 
of  its  velocity  for  every  second  that  it  falls. 

QUESTION  166.  In  what  way  can  we  determine  how  much  force  is  re- 
quired to  move  the  reciprocating  parts  of  an  engine  at  the  beginning  of  the 
stroke  ? 

Answer.  To  make  this  plain  let  it  be  supposed  that  the  weight  of  the 
piston  and  other  reciprocating  parts  is  concentrated  at  A , fig.  90,  and  that 
the  crank  is  at  the  dead-point,  B.  It  has  been  explained,  that  if  a crank- 
pin,  F,  is  in  the  position  shown  in  fig.  95,  and  is  revolving  about  the 


G 


w 

Fig.  95.  Fig.  96. 

Diagrams  showing  Movement  of  Crank.  Scale  in.=l  ft. 


centre  of  the  shaft,  S,  its  tendency  would  be  to  move  in  the  direction  of 
the  line,  F w,  at  right  angles  to  the  crank,  but  this  movement  is  resisted 
by  the  crank  which  draws  the  pin  towards  the  shaft,  S.  Referring  again 
to  fig.  90,  and  supposing  as  before  that  the  weight  of  the  reciprocating 
parts  is  concentrated  at  A,  and  that  A is  connected  to  the  crank-pin  at  B, 
by  a connecting-rod,  A B,  and  it  will  be  obvious  that  while  the  crank-pin 
is  revolving  any  distance,  say  from  i to  2 , that — excepting  so  far  as  their 
movement  is  effected  by  the  angularity  of  the  connecting-rod — the  hori- 
zontal movement  of  the  reciprocating  parts  from  A,  will  be  coincident 
with  or  be  the  same  as  that  of  the  crank-pin  from  B.  As  the  crank-pin 
and  the  reciprocating  parts  are  connected  together  by  the  connecting-rod, 


108 


Catechism  of  the  Locomotive. 


if  their  weight  was  concentrated  in  the  centre  of  the  crank-pin  at  B,  the 
horizontal  movement  of  the  weight  would  then  be  the  same  as  it  is  from  A, 
and  the  force  required  to  move  it  horizontally  from  B,  would  be  equal  to 
that  needed  to  move  it  from  A.  We  may,  therefore,  assume  that  the  weight 
of  the  reciprocating  parts  is  concentrated  at  the  centre  of  the  crank-pin,  and, 
as  shown  in  fig.  95,  that  the  latter  is  at  F,  one  of  the  dead-points.  In  this 
case  the  crank,  F S,  is  supposed  to  be  horizontal,  and  the  crank-pin,  F,  to 
be  moving  in  the  direction  indicated  by  the  dart.  As  already  remarked, 
the  tendency  of  the  weight  concentrated  about  the  centre  of  the  pin,  F, 
will  be  to  move  in  a straight  line,  Fw , at  right  angles  to  the  centre  line, 
F S,  of  the  crank,  as  is  shown  by  the  way  that  water  flies  from  a rapidly 
revolving  grindstone,  or  sand  from  a carriage-wheel.  This  tendency  of 
the  weight  to  continue  moving  in  a straight  line,  causes  it  to  exert  a force 
upon  the  crank — the  same  as  that  exerted  on  a string  when  a stone  or 
other  heavy  object  attached  to  it  is  whirled  around — and  this  is  called  the 
centrifugal  force.  The  resistance  of  the  crank  tending  to  pull  the  weight 
towards  the  centre  of  the  shaft  is  called  the  centripetal force.  As  explained 
above,  if  the  weight  is  concentrated  at  the  centre  of  the  cross-head  pin  at 
A,  fig.  90,  and  it  was  connected  to  the  crank-pin,  at  B,  by  a rod,  as  it  is  in 
a steam-engine,  just  as  much  force  would  be  required  to  pull  the  weight 
toward  the  path  of  the  crank-pin  as  would  be  needed  if  their  weight  was 
concentrated  at  B.  Consequently,  if  we  ascertain  the  centrifugal  force 
which  a weight  equal  to  that  of  the  reciprocating  parts  of  an  engine  would 
exert  on  the  crank  when  it  is  at  a dead-point,  we  will  know  the  force 
required  to  move  those  parts  in  a horizontal  direction  at  the  beginning 
of  the  stroke. 

Question  167.  How  can  the  centrifugal  force  of  a revolving  body  be 
calculated? 

Answer.  Multiply  the  weight  of  the  revolving  body  in 

POUNDS,  THE  SQUARE  OF  THE  NUMBER  OF  REVOLUTIONS  PER  MINUTE, 
THE  RADIUS  OR  DISTANCE  IN  FEET  FROM  THE  CENTRE  OF  MOTION, 
AND  .00034  TOGETHER,  AND  THE  PRODUCT  WILL  BE  THE  CENTRIFUGAL 
FORCE  IN  POUNDS. 

Question  168.  How  can  we  ascertain  how  much  force  is  required  to 
accelerate  the  piston  at  any  point  after  the  crank  has  passed  beyond  the  dead- 
point  ? 

Answer.  To  explain  this  it  will  be  supposed  that  the  crank  is  in  the 
position,  F S,  shown  in  fig.  96.  The  mass,  whose  weight  it  will  again  be 
supposed  is  concentrated  at  the  centre,  F,  of  the  crank-pin,  would  then,  if 


Piston,  Connecting-Rod  and  Crank. 


109 


left  to  itself,  move  in  a direction,  indicated  by  F w,  at  right  angles  to  the 
crank,  F S.  The  centrifugal  force  again  pulls  F away  from  the  centre,  S, 
and  acts  in  the  direction  of  S F.  It  will  be  plain  that  when  the  crank  is 
in  this  position,  that  it  is  only  that  portion  of  the  centrifugal  force  which 
acts  horizontally  that  accelerates  or  pulls  the  reciprocating  parts  in  that 
direction.  Therefore,  if  F S is  equal  to  the  centrifugal  force  by  drawing  a 
parallelogram  of  forces,  B S c F,  with  F S for  the  diagonal,  and  the  sides, 
B S and  F c,  horizontal,  and  B F and  S c perpendicular,  then  by  the 
„ principles  already  explained,  B S and  F c will  represent  the  horizontal 
component  or  the  horizontal  pull  exerted  by  the  centrifugal  force  acting 
on  the  crank  when  it  is  in  the  position  shown  in  fig.  96.  Similar  diagrams 
will  show  the  horizontal  pull  of  the  centrifugal  force  for  any  position  of 
the  crank.* 

Question  169.  What  would  be  the  centrifugal  force  of  the  reciprocating 
parts  of  a locomotive  which  weigh  jjo  lbs.,  if  it  has  driving-wheels  j feet 
in  diameter,  cylinders  with  2 feet,  stroke,  and  is  running  jo  miles  an  hour  ? 

Answer.  By  a simple  calculation  it  will  be  found  that  at  50  miles  an 
hour  wheels  5 feet  in  diameter  would  make  280  turns  in  a minute.  By 
the  rule  given  in  answer  to  Question  158  we  would  have : 

550  x 280  x 280  x 1 x .00034=14,660  lbs. 

QUESTION  170.  How  can  the  pressure  required  to  accelerate  the  piston, 
during  a whole  stroke,  be  shown  by  a diagram  ? 

Answer.  It  has  been  explained  that  the  pressure  required  at  the  begin- 
ning of  the  stroke  will  be  equal  to  the  centrifugal  force  of  the  weight  of 
the  reciprocating  parts,  if  it  was  concentrated  at  the  centre  of  the  crank- 
pin.  Horizontal  components  of  the  centrifugal  force  for  different  posi- 
tions of  the  crank  can  be  ascertained  by  diagrams  similar  to  fig.  96.  Hav- 
ing done  this,  a line,  A E,  fig.  97,  may  be  laid  off  equal  to  the  stroke  of 
the  piston,  and  a perpendicular,  A c,  can  be  drawn  from  the  extremity,  A, 
whose  length  is  equal  to  the  centrifugal  force.  From  B at  a distance  A 
B= to  A B,  of  fig.  96,  a perpendicular,  B d,  is  drawn  equal  to  the  horizon- 
tal component,  F c,  of  the  centrifugal  force,  as  shown  in  fig.  96.  Other 
lines,  as  C e,  may  be  drawn  representing  the  action  of  the  centrifugal  force 
when  the  crank  and  piston  are  in  other  positions.  If  now,  a line,  c d e D, 
is  drawn  through  the  extremities  of  the  perpendiculars,  it  will  be  found 
to  be  a straight  line,  which  will  intersect  the  centre,  D,  of  the  line,  A E, 


* In  this  explanation  no  account  has  been  taken  of  the  effect  of  the  angularity  of  the  connect- 
ing-rod, which  has  some,  although  not  a very  great  influence  on  the  centrifugal  action  at  the 
crank-pin. . 


110 


Catechism  of  the  Locomotive. 


representing  the  stroke ; so  that  to  make  a diagram  of  this  kind,  all  we 
need  do  is  to  calculate  the  centrifugal  force  and  represent  it  by  a perpen- 
dicular, A c,  at  the  end  of  a line  representing  the  stroke,  and  then  draw 
a straight  line  through  its  extremity,  c,  and  a point,  D,  in  the  middle  of 
the  line,  A E. 

Question  171.  Is  the  power  required  to  accelerate  the  piston  in  moving 
from  the  beginning  to  the  middle  of  the  stroke  lost  ? 

Answer.  No.  The  power  represented  by  the  momentum  of  the  recip- 
rocating parts  is  communicated  by  the  connecting-rod  to  the  crank-pin 
after  the  piston  has  passed  the  middle  of  its  stroke.  It  has  been  ex- 
plained that  the  horizontal  movement  of  the  crank-pin  is  accelerated 
during  the  first  quarter  of  its  revolution,  and  is  retarded  during  the  second. 
Consequently,  during  the  latter  period  the  crank-pin  resists  the  accelerated 
motion  or  momentum  of  the  reciprocating  parts,  which,  therefore,  press 
against  it,  and  thus  do  work. 

QUESTION  172.  How  may  the  effect  of  this  momentum  of  the  recipro- 
cating parts  be  shown  in  the  diagram  ? 

Answer.  During  the  first  half  of  the  stroke,  as  has  been  explained, 
pressure  must  be  exerted  against  the  piston  to  start  the  reciprocating 
parts  from  a state  of  rest,  and  then  accelerate  their  motion  up  to  a point 
about  the  middle  of  the  stroke.  After  that  the  momentum  of  these  parts 
exerts  a pressure  against  the  crank-pin. 

QUESTION  173.  How  does  the  diagram  show  the  momentum  of  the  re- 
ciprocating parts  ? 

Answer.  In  fig.  97  the  vertical  distance  of  the  diagonal  line,  c D,  below 


Fig.  97.  Diagram  showing  Inertia  and  Momentum  of  Piston.  Scaled  in. =1  ft. 

the  horizontal  line,  A E,  represents  the  pressure  which  must  be  exerted 
to  start  and  accelerate  the  reciprocating  parts.  After  the  piston  has 
reached  its  maximum  velocity  near  the  middle  of  the  stroke  the  motion 
of  these  parts  is  retarded  by  the  crank-pin,  and  they  consequently  press 


Piston,  Connecting-Rod  and  Crank. 


Ill 


against  it.  During  the  first  half  of  the  stroke  these  parts  resist  accelera- 
tion, and  during  the  latter  part  they  resist  retardation.  Or,  in  plainer 
language,  in  the  one  case  they  hold  back,  and  in  the  other  they  push  the 
crank  ahead.  The  forces  exerted  during  the  two  portions  of  the  stroke 
are,  therefore,  of  opposite  kinds.  For  that  reason  the  force  of  momentum 
of  the  reciprocating  parts  is  laid  off  on  the  opposite  side  of  the  line,  A E. 
As  the  momentum  of  a moving  body  is  just  equal  to  the  force  required  to 
produce  the  motion,  if  there  has  been  no  loss  of  energy  from  friction  or 
other  causes,  the  unshaded  portion,  D f E,  of  the  diagram  above  the  line, 
A E,  would  represent  the  pressure  which  the  reciprocating  parts  exert 
against  the  crank-pin,  and  is  just  equal  to  c A D.  This  can  be  proved  by 
constructing  parallelograms  of  force  for  the  last  half  in  the  same  way  as 
was  explained  for  the  first  half.  It  would  thus  be  found  that  the  horizon- 
tal components  of  the  centrifugal  force  of  the  reciprocating  parts  in  the 
different  positions  of  the  crank  are  the  same  for  the  last  half  as  they  are 
for  the  first  half  of  the  stroke,  if  the  effect  of  the  angularity  of  the  con- 
necting-rod is  not  taken  into  consideration. 

QUESTION  174.  What  influence  does  the  angularity  of  the  connecting- 
rod  have  on  the  pressure  required  to  accelerate  and  retard  the  reciprocating 
parts  ? 

Answer.  It  has  been  shown  from  fig.  90  that  the  rate  of  accelera^on  of 
the  piston  during  the  backward  stroke  is  greater  than  it  is  for  the  forward 
stroke,  and  the  rate  of  retardation  is  greater  for  the  forward  stroke  than 
for  its  backward  movement.  Consequently,  if  the  effect  of  the  connect- 
ing-rod is  taken  into  account  the  pressure  represented  by  A c,  in  fig.  97, 
would  be  somewhat  increased,  and  that  shown  by  f E would  be  diminished. 

The  effect  of  the  connecting-rod  in  thus  increasing  and  diminishing  the 
pressure  required  to  accelerate  and  retard  the  reciprocating  parts  at  the 
two  ends  of  the  stroke  is  equal  to  the  proportion  which  the  length  of  the 
crank  bears  to  the  connecting-rod.  That  is,  in  fig.  90,  the  crank  is  \ the 
length  of  the  rod,  so  that  \ must  be  added  to  the  centrifugal  force,  which 
is  equal  to  the  pressure  required  to  accelerate  the  parts  when  the  piston 
is  at  the  front  end  of  the  cylinder,  and  \ must  be  deducted  when  the 
piston  is  at  the  back  end.  The  line,  b D g,  fig.  97,  will  then  be  curved  as 
shown  by  the  dotted  line.* 

* The  proof  of  this  is  given  in  a note  to  the  answer  to  Question  435.  The  subject  is  fully  dis- 
cussed in  Arthur  Riggs’s  “ Practical  Treatise  on  the  Steam-Engine,”  in  George  V.  Holmes’s 
book  on  the  same  subject,  and  in  “ A Treatise  on  the  Richards’s  Steam-Engine  Indicator,”  by 
Charles  T.  Porter. 


CHAPTER  X. 


GENERAL  DESCRIPTION  OF  A LOCOMOTIVE  ENGINE. 

Question  175.  What  are  the  principal  parts  of  an  ordinary  locomotive 
engine  ? 

Answer.  A boiler  for  generating  steam  and  a pair  of  high-pressure 
steam-engines,  which  are  all  mounted  on  suitable  frames  and  wheels 
adapted  for  running  on  a track  consisting  of  two  iron  or  steel  rails. 

Question  176.  How  is  the  power  of  high-pressure  engines  applied  to 
locomotives  ? 

Answer.  By  connecting  the  engines  with  the  wheels  so  as  to  give  the 
the  latter  a rotary  motion. 

Question  177.  When  the  wheels  revolve  what  will  occur? 

Answer.  Either  they  will  slip  on  the  track,  or  the  locomotive  will  move 
backward  or  forward  according  to  the  direction  the  wheels  are  turning. 

QUESTION  178.  What  will  determine  whether  the  wheels  will  slip  or 
the  locomotive  m.ove  ? 

Answer.  The  friction  or  adhesion , as  it  is  called,  between  the  wheels 
and  the  track.  If  this  adhesion  is  greater  than  the  resistance  opposed  to 
the  movement  of  the  locomotive,  the  latter  will  overcome  the  resistance ; 
but  if  the  latter  is  greater  than  the  friction,  the  wheels  will  slip. 

Question  179.  Upon  what  does  the  amount  of  friction  or  adhesion  of 
the  wheels  depend? 

Answer.  Chiefly  on  the  weight  which  they  bear,  but  to  some  extent 
upon  the  condition  of  the  rails.  Under  ordinary  circumstances,  the  ad- 
hesion of  the  wheels  of  a locomotive  is  in  direct  proportion  to  the  weight 
they  carry. 

Question  180.  Why  are  two  cylinders  employed  on  locomotives  ? 

Answer.  Because  if  only  one  was  used,  it  would  be  impossible  or  very 
difficult  to  start  the  engine,  if  it  should  stop  on  one  of  the  dead-points. 

Question  181.  How  is  this  difficulty  overcome  by  the  use  of  two  cyl- 
inders ? 

Answer.  By  attaching  the  two  cranks  to  the  same  shaft  or  axle,  and 
placing  them  at  right  angles  to  each  other,  so  that  when  the  one  is  at  a 


General  Description  of  a Locomotive  Engine. 


113 


dead  point  the  other  is  in  a position  where  the  steam  can  exert  the  maxi- 
mum power  on  the  crank. 

Question  182.  How  are  the  cranks  of  an  ordinary  locomotive  made? 

Answer  They  are  cast  in  one  piece  with  the  wheels  that  drive  the 
locomotive,  which  are  therefore  called  driving-wheels.  In  this  country 
the  centre  portion  of  such  wheels,  or  wheel-centres  as  they  are  called,  are 
always  made  of  cast-iron.  They  are  bored  out  accurately  so  as  to  fit  the 
axles,  which  are  forced  into  the  holes  bored  to  receive  them.  The  centres 
are  keyed  fast  to  the  axles,  so  as  to  prevent  them  from  turning.  The 
wheel-centres  have  steel  tires  around  the  outside  which  are  accurately 
turned  inside,  and  are  made  a little  smaller  than  the  wheel-centres.  Be- 
fore they  are  put  on  the  wheels  the  tires  are  expanded  by  heating  them, 
and  are  then  put  on  the  wheel-centres,  and  as  they  cool  they  contract, 
which  causes  them  to  fit  tight.  The  axle  of  a locomotive  engine  to  which 
the  pistons  are  connected  is  called  the  main  driving-axle , and  the  wheels 
attached  to  it  the  main  driving-wheels. 

Question  183.  What  is  the  general  construction  and  arrangement  of 
the  farts  of  a locomotive? 

Answer.  The  construction  and  arrangement  of  parts  of  an  ordinary  loco- 
motive is  shown  by  Plates  III,  IV  and  V,  which  represent  a side  view,  a 
longitudinal  section,  and  a plan  of  an  8-wheeled  passenger  engine  built  at 
the  Baldwin  Locomotive  Works  in  Philadelphia,  and  by  fig.  98,  which  is  a 
transverse  section  through  the  cylinders,  and  fig.  99,  which  is  an  end  view 
looking  at  the  back  end  of  the  engine.* 

Question  184.  How  are  the  cylinders  and  drivmg-wheels  of  a locomo- 
motive  usually  placed? 

Answer.  The  cylinders,  1,  of  8-wheeled  American  passenger  engines, 
Plates  III,  IV  and  V,  and  figs.  98  and  99,  are  placed  at  the  front  end  of 
the  locomotive,  and  the  main  driving-axle,  2,  far  enough  behind  them 
to  permit  the  connecting  rods,  3,  to  be  attached  to  pins,  5,  called  crank- 
pins , in  cranks,  in  the  wheels.  In  this  country  the  wheels  and  cranks  are 
now  universally  placed  on  the  outside  of  the  frames,  and  therefore  the 
cylinders  must  be  placed  far  enough  apart  (as  shown  in  fig.  98  and  Plate 
V)  to  permit  the  connecting-rods  to  be  attached  to  the  crank-pins.  For 
this  reason  the  cylinders  are  also  placed  outside  of  the  frames,  32  32  32. 
The  frames,  it  will  be  seen,  are  inside  of  the  wheels,  and  the  cylinders  now 
nearly  always  have  their  axes  or  centre-lines  horizontal,  although  in  old 
engines  they  are  sometimes  inclined.  The  cranks  on  the  one  side  of  the 

* The  same  figures  indicate  the  same  parts  in  all  these  engravings. 


Fig.  98.  Transverse  Sections  through  Smoke  Box  of  Locomotive.  Scale  % in.=l  ft, 


116 


Catechism  of  the  Locomotive. 


locomotive,  as  has  been  explained,  are  placed  at  right  angles  to  those  on 
the  other,  so  that  when  those  on  one  side  are  at  their  dead-points,  those 
on  the  other  are  half  way  between  the  dead-points.  They  are  arranged  in 
this  way  so  that  the  piston  on  one  side  can  exert  its  maximum  power 
when  the  cranks  on  the  other  side  are  at  their  dead-points. 

Question  185.  Why  are  more  than  one  pair  of  driving-wheels  necessary 
for  locomotives  ? 

Answer.  Because  if  all  the  weight  which  is  needed  to  create  the 
requisite  adhesion  of  the  wheels  of  locomotives  to  pull  heavy  loads  was 
placed  on  one  pair  of  wheels  the  weight  would  be  so  excessive  as  to  partly 
crush  and  injure  the  rails.  It  is  therefore  distributed,  usually  on  two 
pairs,  but  sometimes  on  three  or  four  or  even  more  pairs.  The  cranks  in 
the  wheels  on  each  side  of  the  engine  are  connected  together  by  rods  or 
bars,  4,  called  coupling  ox  parallel-rods,  which  are  attached  to  the  crank- 
pins,  so  that  all  the  driving-wheels  will  revolve  together. 

Question  186.  Where  is  the  second  pair  of  driving-wheels  usually 
placed? 

Answer.  These  wheels,  8 8 — called  the  back  driving  or  trailing  driving- 
wheels — are,  in  the  ordinary  type  of  locomotives  used  in  this  country, 
situated  behind  the  main  driving-wheels,  far  enough  back  to  give  the  room 
necessary  for  the  fire-box  between  the  two  axles. 

QUESTION  187.  How  are  the  axles,  cylinders,  etc.,  held  in  the  right  posi- 
tion in  relation  to  each  other  ? 

Answer.  By  the  longitudinal  frames,  32  32,  which  hold  the  axles  in  the 
proper  place,  and  are  bolted  to  the  cylinders,  and  are  also  fastened  to  the 
boiler  at  10  10. 

Question  188.  What  are  the  smaller  wheels,  6 6,  called,  and  what  are 
they  for  ? 

Answer.  They  are  called  truck-wheels,  and  carry  the  weight  of  the 
cylinders  and  other  parts  of  the  front  end  of  the  locomotive,  and  serve  to 
guide  and  steady  the  machine  in  a manner  which  will  be  more  fully  ex- 
plained hereafter. 

Question  189.  How  is  a locomotive  engine  made  to  run  either  backward 
or  forward? 

Answer.  By  having  two  eccentrics,  11  11',  Plates  IV  and  V,  for  each 
cylinder.  One  of  these  is  fixed  or  set  on  the  shaft  in  such  a position  as  to 
move  the  valve  so  that  the  engine  will  run  in  one  direction ; the  other 
eccentric  is  set  so  that  the  engine  will  run  the  reverse  way.  The  ends  of 
each  pair  of  eccentric  rods  are  attached  by  rods,  12  12',  to  what  is  called 


General  Description  of  a Locomotive  Engine. 


117 


4 link,  13,  the  object  of  which  is  to  furnish  the  means  of  quickly  engaging 
and  disengaging  either  eccentric  rod  to  or  from  the  rocker,  14,  14.  The 
rockers  are  connected  to  the  main  valves,  33,  by  rods,  34,  called  valve- 
stems.  The  links  are  suspended  by  bars,  15,  called  link-hangers,  to  the 
ends  of  arms,  16,  attached  to  a shaft,  17,  called  a lifting-shaft.  This  shaft 
has  another  upright  arm,  18,  attached  to  it  on  the  right-hand  side  of  the 
engine,  the  upper  end  of  which  is  connected  by  a rod,  19  21,  called  the 
r ever  sing-rod,  to  a lever,  20  21  and  22,  called  the  r ever  sing-lever , in  the 
cab.  The  principles  and  operation  of  this  mechanism  will  be  fully  ex- 
plained in  another  chapter. 

QUESTION  190.  What  are  the  principal  parts  or  “ organs ” of  a locomo- 
tive boiler  ? 

Answer.  1.  A fireplace,  or,  as  it  is  called,  a fire-box,  9. 

2.  A cylindrical  part,  23,  attached  to  the  fire-box  at  one  end  and  to  a 
chamber,  24,  called  the  smoke-box,  at  the  other. 

3.  The  tubes  or  flues,  25  25',  Plate  IV,  which  connect  the  fire-box  with 
the  smoke-box,  and  pass  through  the  cylindrical  part  of  the  boiler  and  are 
surrounded  with  water. 

4.  The  chimney  or  s7noke-stack,  25. 

Question  191.  What  is  each  of  those  parts  or  organs  for  and  of  what 
do  they  consist  ? 

Answer.  The  fire-box,  9,  furnishes  the  room  for  burning  the  fuel,  and 
consists  of  an  inner  and  outer  shell  made  of  boiler  plate,  as  shown  in 
Plates  IV  and  V,  with  the  spaces,  26  26,  between  the  two  shells  filled  with 
water ; a grate,  27  27,  formed  of  cast-iron  bars,  with  spaces  between  them 
for  admitting  air  for  the  combustion  of  the  fuel,  which  is  placed  on  top  of 
them ; a door,  28,  called  the  furnace-door,  for  supplying  the  grate  with 
fuel ; a receptacle,  29,  below  the  grate,  to  collect  ashes,  and  therefore 
called  the  ash-pan,  which  is  supplied  with  suitable  dampers,  30  and  31,  for 
admitting  or  excluding  the  air  from  the  fire. 

The  cylindrical  part,  23,  or  waist  of  the  boiler,  as  it  is  sometimes  called, 
contains  the  greater  part  of  the  water  to  be  heated. 

The  flues  or  tubes,  as  they  are  generally  called,  are  usually  2 inches  in 
diameter  and  from  10  to  12  feet  long.  The  number  of  tubes  in  a locomo- 
tive boiler  varies  with  its  size.  A boiler  of  the  size  represented  in  the 
illustration  has  about  250  tubes,  as  shown  in  fig.  91.  They  conduct  the 
smoke  and  products  of  combustion  from  the  fire-box  to  the  smoke-box. 
The  tubes  are  made  of  small  diameter  so  as  to  subdivide  the  smoke  into 
many  small  streams  and  thus  expose  it  to  a large  radiating  surface  through 
which  the  heat  is  conducted  to  the  water. 


118 


Catechism  of  the  Locomotive. 


The  chimney  or  smoke-stack  serves  partly  for  removing  into  the  open 
air  the  smoke  which  passes  through  the  flues,  and  partly  for  producing  a 
strong  draft  of  air,  which  is  indispensably  necessary  for  the  rapid  combus- 
tion of  the  fuel.  Smoke-stacks  are  also  often  provided  with  arrangements 
for  arresting  the  sparks  and  cinders  which  escape  from  the  fire. 

QUESTION  192.  What  is  a locomotive  head-light , and  what  is  it  for? 

Answer.  A head-light  is  a large  lamp,  35,  Plate  III,  which  is  placed  on 
the  front  end  of  a locomotive  to  light  up  the  track  in  front  of  it  and  give 
warning  of  its  approach. 

Question  193.  What  is  a cow-catcher,  and  what  is  it  for  ? 

Answer.  A cow-catcher , 38,  sometimes  called  a “ pilot,"  as  its  name 
implies,  is  intended  to  “ catch  cows”  or  other  obstructions  on  the  track 
and  throw  them  off,  thus  preventing  them  from  getting  under  the  wheels 
while  the  engine  is  running.  It  is  a triangular-shaped  structure  made  of 
wooden  or  iron  bars  and  attached  to  the  front  of  the  engine. 

Question  194.  What  is  a sand-box  on  a locomotive  for? 

Answer.  The  sand-box,  39,  is  usually  placed  on  top  of  the  boiler,  and 
has  pipes,  40,  on  each  side  of  the  engine  by  which  sand  is  conducted  to 
the  rails  in  front  of  the  driving-wheels,  to  prevent  them  from  slipping 
when  the  engine  is  working  hard. 

QUESTION  195.  What  is  the  cab  of  a locomotive  for  ? 

Answer.  A cab,  43,  is  for  the  protection  of  the  men  who  run  the  engine 
from  rain,  cold  and  sunshine. 

QUESTION  196.  How  is  the  locomotive  connected  to  the  train  behind  it? 

Answer.  By  an  iron  bar,  48,  called  a draw-bar,  which  is  attached  by  a 
pin,  49,  Plate  IV,  to  a casting  on  the  back  end  of  the  engine.  The  draw- 
bar is  coupled  to  the  tender  behind  the  engine  by  another  pin  similar  to 
the  one  on  the  engine.  The  engine  and  tender  are  also  coupled  together 
by  chains,  50,  called  safety-chains.  These  are  used  as  a safeguard  to  pre- 
vent the  engine  and  tender  from  separating  in  case  the  draw-bar  should 
break. 

Question  197.  How  are  the  water  and fuel  carried  which  must  be  sup- 
plied to  a locomotive  while  it  is  running  ? 

Answer.  The  water  is  carried  in  a tank,  which  is  usually  constructed 
in  the  form  of  a letter  U.  so  as  to  give  room  for  the  stowage  of  fuel  be- 
tween its  two  branches  or  sides,  and  is  carried  on  a set  of  wheels,  which 
forms  a separate  vehicle,  independent  of  the  locomotive,  called  a tender , 
the  construction  of  which  will  be  explained  in  a future  chapter.  In  another 
class  of  engines,  called  tank-engines , the  water-tank  and  fuel  are  carried 
on  the  engine. 


General  Description  of  a Locomotive  Engine. 


119 


THE  FOLLOWING  IS  A 


LIST  OF  PARTS  DESIGNATED  BY  THE  NUMBERS  ON  PLATES  III,  IV,  V,  AND 

FIGS.  98  AND  99. 


1.  Cylinders. 

2.  Main  driving-axle. 

3.  Connecting-rod. 

4.  Coupling-rod. 

5.  Main  crank-pin. 

6.  Truck  wheels. 

7.  Main  driving-wheels. 

8.  Back  driving  or  trailing  wheels. 

9.  Fire-box. 

10.  Expansion  clamps. 

11.  Eccentrics. 

12.  Eccentric-rods. 

13.  Link. 

14.  Rocker. 

15.  Link-hanger. 

16.  Horizontal  arm  of  lifting-shaft. 

17.  Lifting-shaft. 

18.  Upright  arm  of  lifting-shaft. 

19.  Reversing-rod. 

20.  'l 

21-  r Reversing-lever. 

22.  j 

23.  Cylinder,  or  waist  of  boiler. 

24.  Smoke-box. 

25.  Chimney  or  smoke-stack. 

26.  . Water  spaces. 

27.  Grate. 

28.  Furnace-door. 

29.  Ash-pan. 

30.  Front  ash-pan  damper. 

31.  Back  ash-pan  damper. 


32.  Frames. 

33.  Main-valve. 

34.  Valve-stem. 

35.  Head-light. 

36.  Head-light  reflector. 

37.  Head-ligh'  lamp. 

38.  Cow-catcher. 

39.  Sand-box. 

40.  Sand-pipes. 

41.  Bell. 

42.  Dome. 

43.  Cab. 

44.  Safety-valve. 

45.  Safety-valve  lever. 

46.  Whistle. 

47.  Whistle-lever. 

48.  Draw-bar. 

49.  Coupling-pin. 

50.  Safety-chains. 

51.  Throttle-lever. 

52.  Injector. 

53.  Injector  steam-pipe. 

54.  Injector  feed-pipe. 

55.  Injector  check-valve. 

56.  Running-board. 

57.  Hand-rail. 

58.  Equalizing-lever. 

59.  ^Driving-springs. 

60.  Counter-balance  weights. 

61.  Driving-wheel  guard. 

62.  Guide-bar. 


120  Catechism  of  the  Locomotive. 

63.  Cross-head. 

89.  Throttle-stem. 

64.  Piston. 

90.  Throttle  bell-crank. 

65.  Piston-rod. 

91.  Steam-gauge. 

66.  Steam-chest. 

92.  Steam-gauge  lamp. 

67.  Spark  ejector  valve. 

93.  Whistle  lever. 

6S.  Relief-valve  for  steam-chest. 

94.  Gauge-cocks. 

69.  Spark  ejector. 

95.  Foot-board. 

70.  Smoke-box  door. 

96.  Truck  centre-bearing. 

71.  Cylinder-cocks. 

97.  Truck  centre-plate. 

72.  Cylinder-cock  lever. 

98.  Truck  centre-pin. 

73.  Cylinder-cock  shaft. 

99.  Whistle-shaft. 

74.  Truck-spring. 

100.  Suction-pipes. 

75.  Truck-frame. 

101.  Foot-steps  of  cab. 

76.  Truck  equalizing-lever. 

102.  Hand-holes  of  cab. 

77.  Truck  wheel-guaiu. 

103.  Front  door  of  cab. 

78.  Truck  check-chain. 

104.  Water-gauge. 

79.  Push-bar. 

105.  Stand  for  oil-cans. 

80.  Exhaust-pipes 

106.  Drip  for  gauge-cocks. 

81.  Exhaust-nozzle. 

107.  Injector- valve. 

82.  Deflector. 

108.  Oil-cup  for  oiling  main  valves. 

83.  Wire-netting. 

109.  Handle  for  opening  valves  in  sand-box 

84.  Steam-pipe. 

110.  Handle  for  opening  front  damper. 

85.  T-pipe. 

111.  Bell-crank  for  opening  front  damper 

86.  Dry-pipe. 

112.  Rod  for  opening  front  damper. 

87.  Throttle-pipe. 

113.  Mud-plugs. 

88.  Throttle-valve. 

* 

CHAPTER  XI. 


DIFFERENT  KINDS  OF  LOCOMOTIVES. 

Question  198.  Into  what  classes  may  locomotives  be  divided  conveni- 
ently ? 

Answer.  1.  Locomotives  for  “switching,”  “shunting,”  or  “drilling” 
service — that  is,  for  transferring  cars  from  one  place  to  another  at  stations; 
2,  for  freight  traffic ; 3,  for  ordinary  passenger  traffic  ; and  4,  for  metro- 
politan or  suburban  railroads,  where  a great  many  light  trains  are  run. 

QUESTION  199.  What  kinds  of  locomotives  are  used  in  this  country  for 
switching  cars  at  stations? 

Answer.  Four  and  six-wheeled  locomotives  similar  to  those  represented 
by  figs.  100  and  101.  Such  engines  are  now  usually  made  with  separate 
tenders,  but  they  are  sometimes  made  so  as  to  carry  the  water-tank  and 
fuel  on  the  locomotive  itself,  as  shown  by  fig.  117,  and  are  then  called  tank 
locomotives. 

QUESTION  200.  Why  are  four  and  six-wheeled  locomotives  used  for 
switching  ? 

Answer.  Because  in  such  service  it  is  necessary  to  start  trains  often, 
many  of  which  are  very  heavy,  and  therefore  a great  deal  of  adhesion  is 
needed.  For  this  reason  the  whole  weight  of  the  locomotive,  and,  in  the 
case  of  some  tank  locomotives,  that  of  the  water  and  fuel,  is  placed  on  the 
driving-wheels.  It  is  also  necessary  for  such  locomotives  to  run  over 
curves  of  very  short  radius  and  into  switches  whose  angle  with  the  main 
track  is  very  great ; and  therefore,  in  order  that  they  may  do  this  and 
remain  on  the  track,  their  wheel-bases  must  be  veiy  short,  and  conse- 
quently the  wheels  are  all  placed  near  together  and  are  usually  between 
the  smoke-box  and  fire-box. 

QUESTION  201.  Why  are  such  locomotives  not  suited for  general  traffic? 

Answer.  Owing  to  the  shortness  of  their  wheel-bases  they  become  very 
unsteady  at  high  speeds,  and  acquire  a pitching  motion,  similar  to  that  of 
a horse-car  when  running  rapidly  over  a rough  track.  This  unsteadiness 
not  only  becomes  very  uncomfortable  to  the  men  who  run  the  locomotive, 
but  when  it  occurs  there  is  danger  of  the  engine  running  off  the  track. 


122 


Catechism  of  the  Locomotive. 


As  nearly  all  switching  is  done  at  very  slow  speeds,  it  is  not  so  objection- 
able for  that  service  as  it  would  be  on  the  “ open  road  ”*  at  high  speeds. 

Question  202.  How  can  such  engines  be  made  to  run  steadier? 

Answer.  By  putting  a pair  of  truck-wheels  under  the  front  or  rear  end 
of  the  engine,  as  shown  in  figs.  102,  103, 104  and  105. 

QUESTION  203.  What  kinds  of  locomotives  are  used  for  passenger 
service  ? 

Answer.  The  greater  part  of  the  passenger  service  of  this  country  is 
performed  by  locomotives  like  that  selected  for  the  illustrations  of  these 
articles,  and  represented  in  Plates  III,  IV  and  V.  Such  locomotives  have 
been  called  “ American  ” locomotives,  because  they  first  originated  in  this 
country,  and  are  now  more  generally  used  here  than  anywhere  else.  Per- 
spective views  of  similar  engines  are  also  shown  in  figs.  110  and  111. 

Question  204.  How  are  such  engines  constructed? 

Answer.  One  pair  of  driving-wheels  is  usually  placed  behind  the  fire- 
box and  one  in  front,  and  the  front  end  of  the  engine  is  carried  on  a four- 
wheeled  truck.  In  some  cases  the  fire-box  is  extended  back  over  the  top 
of  the  rear  axle.  Usually  the  fire-box  is  placed  between  the  frames,  but 
they  are  sometimes  put  on  top,  in  order  that  it  can  be  made  wider  than  is 
possible  if  it  is  placed  between. 

Question  205.  What  are  the  dimensions  of  such  engines? 

Answer.  The  principal  dimensions  of  the  engines  illustrated  by  figs. 
110  and  111  are  given  opposite  the  engravings,  but  locomotives  of  this 
plan  are  built  of  much  smaller  and  also  of  larger  sizes  than  those  represent- 
ed by  the  engravings.  In  some  cases  they  do  not  weigh  more  than  35  or 
36,000  lbs.,  with  cylinders  from  8 to  12  inches  in  diameter.  In  other  cases 
they  weigh  over  100,000  lbs.,  with  cylinders  18  or  20  inches  in  diameter. 
The  wheels  vary  from  4 to  6 feet  in  diameter,  but  the  most  common  sizes 
are  4}  to  5^  feet. 

Question  206.  What  kinds  of  locomotives  are  used for  freight  service  ? 

Answer,  Much  of  the  freight  service  in  this  country  is  performed  by 
“American  ” locomotives,  similar  to  those  described  for  passenger  traffic. 
Usually  engines  used  for  freight  service  have  smaller  driving-wheels  than 
those  designed  for  passenger  trains. 

QUESTION  207.  When  it  is  desirable  to  pull  heavier  loads  than  is  possi- 
ble with  the  adhesive  weight  that  can  be  placed  on  four  driving-wheels, 
what  is  done  ? 


♦The  term  “ open  road ” is  a literal  translation  from  the  German,  for  which  there  is  no  cor- 
responding English  term,  and  means  the  road  between  stations  where  trains  run  fast. 


Different  Kinds  of  Locomotives. 


123 


Answer.  One  or  more  pairs  of  driving-wheels  are  added,  as  in  the  ten- 
wheeled and  “ Mogul”  locomotives  represented  by  figs.  112  and  113,  and 
the  “Consolidation”  and  twelve-wheeled  engines  by  figs.  114  and  115,  and 
the  “ Decapod  ” locomotive  by  fig.  11G.  The  ten-wheeled  locomotive  is  simi- 
lar in  construction  to  an  ordinary  “American  ” locomotive,  excepting  that 
it  has  another  pair  of  driving-wheels  in  front  of  the  main  driving-wheels. 
It  will  be  seen,  however,  that  it  is  necessary  to  keep  these  close  to  the 
latter,  because  if  they  are  brought  further  forward  they  will  be  too  near 
the  back  truck  wheels.  For  this  reason  a truck  consisting  of  a single  pair 
of  wheels  is  often  in  place  of  the  four-wheeled  truck  and  is  placed  in  front 
of  the  cylinders,  as  represented  in  the  engraving  of  the  Mogul  engine,  fig. 
112,  and  the  front  pair  of  driving-wheels  can  then  be  placed  further 
forward,  and  they  thus  bear  a larger  proportion  of  the  weight  than  they 
do  if  located  as  they  are  under  the  ten-wheeled  engine.  There  is  a similar 
difference  between  the  construction  of  the  twelve-wheeled  and  “ Consoli- 
dation” engines,  shown  by  figs.  114  and  115. 

QUESTION  208.  Under  what  circumstances  are  the  different  classes  of 
freight  locomotives  which  have  been  described  employed? 

Answer.  On  comparatively  level  roads,  or  those  having  a light  busi- 
ness, “ American  ” locomotives  are  generally  used  for  freight  as  well  as 
passenger  business.  On  lines  which  have  moderately  heavy  grades  or 
heavy  traffic,  ten-wheeled  and  Mogul  engines  are  used ; and  where  the 
grades  and  traffic  are  both  heavy,  Consolidation  or  twelve-wheeled  engines 
are  employed.  For  excessively  heavy  mountain  grades,  Decapod  loco- 
motives are  employed. 

Question  209.  What  is  meant  by  metropolitan  and  suburban  railroads? 
What  is  the  nature  of  their  traffic  ? 

Answer.  By  metropolitan  railroads  are  meant  railroads  in  large  cities. 
They  may  be  divided  into  two  classes : one  for  carrying  freight  cars  from 
the  outskirts  of  cities  to  the  warehouses  and  stores  at  their  business  cen- 
tres, and  also  from  the  terminus  of  one  road  to  that  of  another.  Metro- 
politan railroads  of  this  kind  are  usually  branches  of  lines  which  extend 
from  the  city.  Locomotives  for  such  traffic  must  have  great  tractive 
power,  in  order  to  pull  heavy  trains ; and  as  the  speed  is  usually  slow,  the 
wheels  and  the  boiler  capacity  may  be  small.  They  must  generally  be 
capable  of  running  through  curves  of  very  short  radius;  and  as  the  traffic 
is  usually  carried  through  the  streets  in  close  proximity  to  buildings,  the 
locomotives  should  be  as  nearly  as  possible  noiseless.  The  other  class  of 
metropolitan  roads  is  for  carrying  passengers.  The  traffic  of  the  latter  is 


124 


Catechism  of  the  Locomotive. 


similar  to  that  usually  carried  on  horse  railroads,  and  consists  almost  ex- 
clusively of  passengers.  Many  light  trains  must  be  run  at  short  intervals 
and  at  comparatively  slow  speeds,  and  therefore  very  light  locomotives 
are  required. 

The  traffic  of  suburban  railroads  consists  chiefly  of  the  transportation 
of  passengers  to  a large  town  or  city  in  the  morning  and  to  their 
homes  in  the  evening.  As  the  largest  number  of  passengers  must  be 
carried  during  a few  hours  in  the  morning  and  evening,  it  is  necessary 
to  run  very  heavy  trains  at  those  times.  As  the  passengers  must  be  dis- 
tributed at  many  stations  which  are  near  together,  it  is  necessary  to  stop 
often ; and  in  order  that  the  average  speed  may  be  reasonably  fast,  the 
trains  must  run  very  rapidly  between  these  stations.  It  is,  therefore,  es- 
sential to  have  heavy  locomotives,  with  more  than  the  usual  proportion 
of  adhesive  weight,  so  that  the  trains  can  be  started  quickly  without  slip- 
ping the  wheels.  The  main  valves  should  also  have  a liberal  amount  of 
travel,  so  that  the  steam  will  be  admitted  to  and  exhausted  from  the  cyl- 
inders quickly.  In  some  cases  it  is  thought  desirable  to  have  locomo- 
tives which  will  run  equally  well  either  way,  so  that  it  will  not  be  neces- 
sary to  turn  them  around  at  each  end  of  the  “ run.” 

QUESTION  210.  What  kinds  of  locomotives  are  used  on  metropolitan 
railroads  ? 

Answer.  For  freight  traffic  ordinary  switching  locomotives,  like  those 
shown  by  figs.  100  and  101,  are  often  employed.  In  some  cases  these  have 
the  water  tanks  on  the  locomotives.  It  often  happens,  though,  that  such 
traffic  must  be  conducted  in  the  streets  of  a city,  and  that  the  noise,  especi- 
ally of  the  exhausting  steam,  is  thus  liable  to  frighten  horses  and  disturb 
the  occupants  of  the  houses.  It  is,  then,  necessary  either  to  condense  the 
exhaust  steam  or  render  its  escape  noiseless,  which  is  done  by  allowing  it  to 
escape  into  the  water-tanks.  Street  locomotives  which  have  a condenser 
similar  to  the  surface  condensers  used  on  marine  engines  are  used  on  the 
New  York  Central  and  Hudson  River  Railroad  in  New  York  City.  The 
exhaust  steam  passes  through  the  condensers  and  then  escapes  into  the 
tanks.  The  latter  are  long  and  narrow,  so  as  to  expose  a great  deal  of 
surface  to  radiation,  and  in  this  way  the  water  which  becomes  heated  by 
the  steam  is  cooled.  The  engines  have  four  driving-wheels  and  vertical 
boilers.  The  cylinders  are  connected  to  a crank-shaft  with  a pinion  on  it, 
which  gears  with  another  wheel  of  larger  size  on  the  driving-axle.  In 
this  way  the  speed  is  reduced,  and  great  tractive  power  can  be  exerted. 
The  whole  of  the  engine  is  enclosed  so  as  to  hide  the  machinery,  the 


Different  Kinds  of  Locomotives. 


125 


sight  of  which  is  supposed  to  frighten  horses.  The  engines  were 
designed  and  patented  by  the  late  A.  F.  Smith,  formerly  Master  Mechanic 
of  that  road. 

For  roads  in  cities  on  which  passengers  almost  exclusively  are  carried,  an 
entirely  different  class  of  locomotive  is  needed.  To  suit  passengers  it  is, 
of  course,  necessary  to  run  a great  many  trains  at  very  short  intervals. 
When  this  is  done  the  trains  are  necessarily  very  light,  and  therefore  only 
light  locomotives  are  needed.  Fig.  105  represents  one  of  the  engines 
used  on  the  New  York  Elevated  Railroad.  These  run  both  ways,  and 
through  curves  of  only  90  feet  radius.  Engines  similar  to  that  shown  by 
fig.  103  are  also  used  on  this  road. 

Question  211.  What  kind  of  locomotives  are  used for  ?netropolitan  and 
suburban  railroads? 

Answer.  The  ordinary  American  eight-wheeled  locomotive  is  used, 
perhaps,  more  than  any  other  kind ; but  a number  of  locomotives,  like 
that  represented  by  fig.  102,  have  been  built  and  are  used  for  this  traffic. 
These  have  one  pair  of  driving-wheels  in  front  of  the  main  pair,  and  a 
Bissell  truck  in  front  of  the  cylinder.  With  this  arrangement  the  driving- 
wheels  bear  a larger  proportion  of  weight  than  they  do  if  arranged  on  the 
ordinary  American  plan  with  a four-wheeled  truck.  Another  plan  is  that 
shown  by  fig.  109.  Such  engines,  it  will  be  seen,  have  a Bissell  truck  at 
each  end,  and  therefore  they  run  equally  well  either  way.  The  water  and 
fuel  is  carried  in  separate  tenders.  In  some  cases  the  tanks  of  such  engines 
are  carried  on  the  top  and  sides  of  the  boiler,  as  shown  in  fig.  117.  When 
they  are  obliged  to  run  only  a short  distance,  and  a small  supply  of  water 
is  needed,  this  arrangement  answers  very  well ; but  it  is  impossible  to  carry  a 
large  supply  of  water  in  this  way  without  overloading  the  wheels  of  the 
locomotive,  and  at  the  same  time  increasing  the  evils  of  a varying  load  on 
the  driving-wheels. 

To  get  over  this  difficulty,  and  at  the  same  time  dispense  with  a ten- 
der, the  frames  are  extended  behind  the  fire-box,  as  shown  by  fig.  103, 
and  the  water-tank  is  placed  on  top  of  this  extension  of  the  frames,  and 
its  weight  is  carried  on  a pony-truck  below  the  frames  and  behind  the  fire- 
box. With  this  arrangement  the  whole  weight  of  the  boiler  and  the  ma- 
chinery is  kept  on  the  driving-wheels,  and  the  water  and  fuel  is  carried  by 
the  truck.  The  load  on  the  driving-wheels  is  therefore  constant. 

When  larger  engines  are  required  and  more  water  must  be  carried,  a 
four-wheeled  truck  is  placed  under  the  back  end  of  the  engine,  as  shown 
by  figs.  104  and  105.  This  form  of  engine  was  first  designed  and  pat- 


126 


Catechism  of  the  Locomotive. 


ented  by  the  Author,  which  must  account  for  the  name  being  coupled 
with  it. 

The  late  William  S.  Hudson  designed  and  built  a number  of  engines 
like  that  shown  by  fig.  108.  These  each  had  a four-wheeled  truck  at  the 
back  end  and  a pony-truck  at  the  front.  A similar  engine,  with  three 
pairs  of  driving-wheels,  and  another  with  a six-wheeled  truck  in  front  are 
shown  by  figs.  106  and  107. 

Question  212.  What  kinds  of  locomotives  are  used  on  street  rail-  . 
roads  ? 

Answer.  Fig.  118  represents  a locomotive  which  is  used  on  street  and 
suburban  railroads.  Its  construction  is  similar  to  that  of  the  engine 
shown  by  fig.  103,  but  it  is  enclosed  with  a large  cab,  so  that  the  working- 
parts  are  not  exposed.  This  is  done  to  prevent  horses  from  being  fright- 
ened. 

Fig.  119  represents  a steam  car  for  street  railroads,  and  fig,  120  shows 
the  running  gear  and  engine  without  the  car  body.  In  this  passengers  are 
carried  in  the  same  vehicle  that  contains  the  engine.  As  shown  in  fig. 
120,  the  engine  has  a vertical  boiler,  and  the  working  parts  of  the  engine 
are  placed  below  the  floor  of  the  car. 

Question  213.  What  is  a compound  locomotive  ? 

Answer.  It  is  a locomotive  in  which  the  steam,  after  it  has  acted  on 
the  piston  of  one  cylinder,  escapes  into  another  and  larger  cylinder,  in 
which  it  acts  on  another  piston,  and  thus  expands  more  than  it  would  if 
confined  to  one  cylinder.  Some  engines  of  this  kind  have  two  cylinders, 
one  large  and  one  small  one,  or  a high  and  a low-pressure  cylinder.  In 
other  cases  there  are  two  high  and  one  low-pressure  cylinder,  and  in  still 
others  two  high  and  two  low-pressure. 

Question  214.  What  advantage  is  claimed  for  the  cotnpound  system  ? 

Answer.  A saving  of  about  15  to  20  per  cent,  of  the  fuel  is  claimed, 
owing  to  the  greater  degree  of  expansion  of  the  steam.  Thus  far  such 
engines  have  been  used  in  this  country  only  in  an  experimental  way,  but 
they  are  now  (1890)  extensively  used  in  Europe. 

Question  215.  What  is  the  difference  between  inside  and  outside  cylin- 
der engines  ? 

Answer.  In  this  country  it  is  the  universal  practice  to  put  the  cylinders 
of  locomotives  outside  of  the  wheels  and  frames,  and  connect  the  pistons 
to  crank-pins  on  the  outside  of  the  wheels.  In  Europe,  especially  in  Eng- 
land, it  is  more  common  to  put  the  cylinders  between  the  frames  and 
wheels,  and  connect  the  pistons  to  cranks  on  the  main  driving-axle. 


Different  Kinds  of  Locomotives. 


127 


Question  216.  What  are  the  relative  advantages  and  disadvantages 
of  these  methods  of  construction  ? 

Answer.  It  is  claimed  that  engines  with  inside  cylinders  run  steadier 
than  those  with  cylinders  outside,  owing  to  the  greater  leverage  which 
the  pistons  of  the  outside  cylinders  exert,  owing  to  their  being  further 
from  the  centre  line  of  the  engine.  This  is  undoubtedly  true ; but  if  loco- 
motives are  made  with  a long  wheel-base,  as  they  may  be  if  one  or  two 
trucks  are  used,  this  leverage  has  very  little  influence  on  the  steadiness  of 
running  of  the  engine.  It  is  also  claimed  that  when  inside  cylinders  are 
used  they  are  better  protected  from  radiation  and  loss  of  heat,  as  they  can 
be  placed  inside  of  the  smoke-box.  On  the  other  hand,  the  great  objec- 
tion to  inside  cylinders  is  the  crank-axles,  which  are  expensive  in  the  first 
place,  and  are  subject  to  frequent  breakage.  The  inside  cylinders  are  also 
more  or  less  inaccessible  for  making  repairs,  and  there  are  limitations  to 
their  size,  if  they  are  put  between  the  frames.  Experience  in  this  country 
has  led  to  the  entire  disuse  of  inside  cylinders  on  locomotives 


128 


Catechism  of  the  Locomotive. 


Fig.  100. 

FOUR-WHEELED  SWITCHING  LOCOMOTIVE. 


Different  Kinds  of  Locomotives.  129 

Fig.  100. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

FOUR-WHEELED  SWITCHING  LOCOMOTIVE, 

BY  THE 

Cooke  Locomotive  and  Machine  Works,  Paterson,  N.  J. 


Total  weight  in  working  order 59,000  lbs. 

Total  weight  on  driving-wheels 59,000 

Diameter  of  driving-wheels 4 ft.  0 in. 

Diameter  of  main  driving-axle  journal 7 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels,  6 ft.  lOf  “ 

Total  wheel-base  of  engine 6 “ lOf  ** 

Total  wheel-base  of  engine  and  tender. 31  “ 5f  “ 

Diameter  of  cylinders 16 

Stroke  of  cylinders 24  “ 

Outside  diameter  of  smallest  boiler  ring 48  “ 

Length  of  fire-box,  inside 4 ft.  0 

Width  of  fire-box,  inside 2 “ 10  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate ’ . 4 “ 3 “ 

Number  of  tubes 150 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 10  ft.  5f  “ 

Grate  surface Ilf  sq.  ft. 

Heating  surface,  fire-box 73  “ “ 

Heating  surface,  tubes 711  “ “ 

Heating  surface,  total 784  “ “ 

Exhaust  nozzles Single. 

Size  of  steam-ports 15£  x If  in. 

Size  of  exhaust-ports 15f  x 2f  “ 

Throw  of  eccentrics 5f  “ 

Greatest  travel  of  valve 5 “ 

Outside  lap  of  valve ...  Of  “ 

Smallest  inside  diameter  of  chimney 1 ft.  4 “ 

Height,  top  of  rail  to  top  of  chimney 12  “ 9 “ 

Height,  top  of  rail  to  centre  of  boiler 5 “ 8f  “ 

Water  capacity  of  tank 2,000  gals* 


SIX-WHEELED  SWITCHING  LOCOMOTIVE. 

THE  ROGERS  LOCOMOTIVE  AND  MACHINE  WORKS,  PATERSON, 


Different  Kinds  of  Locomotives. 


131 


Fig.  101. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

SIX-WHEELED  SWITCHING  LOCOMOTIVE, 

BY  THE 

Rogers  Locomotive  and  Machine  Works,  Paterson,  N.  J. 


Total  weight  in  working  order 85,000  lbs. 

Total  weight  on  driving-wheels. 85,000  “ 

Diameter  of  driving-wheels 4 ft.  2 

Diameter  of  main  driving-axle  journal 7 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels . 10  “ 6 

Total  wheel-base  of  engine 10  “ 6 

Total  wheel-base  of  engine  and  tender 87  “ 1 

Diameter  of  cylinders 17 

Stroke  of  cylinders 24 

Outside  diameter  of  smallest  boiler  ring 51 

Length  of  fire-box,  inside 4 “ 6 

Width  of  fire-box,  inside 2 “ 9£ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 5 “ 0 

Number  of  tubes 123 

Outside  diameter  of  tubes 2£  in. 

Length  of  tubes 13  “ 10£  “ 

Grate  surface 12f  sq.  ft. 

Heating  surface,  fire-box 83  “ “ 

Heating  surface,  tubes 1,005  “ “ 

Heating  surface,  total 1,088  “ “ 

Exhaust  nozzles Double. 

Size  of  steam-ports 14£xl£  in. 

Size  of  exhaust-ports 14£  x 2£ 

Throw  of  eccentric 5 

Greatest  travel  of  valve , 5 

Outside  lap  of  valve 0££ 

Smallest  inside  diameter  of  chimney 1 ft.  3 

Height,  top  of  rail  to  top  of  chimney 14  “ 6 

Height,  top  of  rail  to  centre  of  boiler 6 “ 3£ 

Diameter  of  tender  truck-wheels 2 “ 9 


Water  capacity  of  tank. 


2,000  gals. 


132 


Catechism  of  the  Locomotive. 


BY  THE  GRANT  LOCOMOTIVE  WORKS,  PATERSON, 


Different  Kinds  of  Locomotives. 


133 


Fig.  102. 

DIMENSIONS,  WEIGHT,  ETC., 

OK 

GRANT  PONY  LOCOMOTIVE, 

BY  THE 

Grant  Locomotive  Works,  Paterson,  N.  J. 


Diameter  of  driving-wheels 4 ft.  2 in. 

Diameter  of  truck-wheels ......  2 “ 4 

Number  of  driving-wheels 4 

• Number  of  truck-wheels 2 

Diameter  of  cylinders 14  in. 

Stroke  of  cylinders 22  “ 

Length  of  fire-box,  inside ..  . 6 ft.  1^  in. 

Width  of  fire-box,  inside 2 “ 9|=  “ 

Number  of  tubes 126 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 7 ft.  10T5^-  “ 

Water  capacity  of  tank 1,498  gals. 


Note.  The  original  drawings  of  this  engine  were  destroyed  by  the  fire  at  the  works,  in 
September,  1887,  so  that  full  specifications  could  not  be  obtained. 


134 


Catechism  of  the  Locomotive. 


FORNEY  PONY  LOCOMOTIVE. 


Different  Kinds  of  Locomotives. 


135 


Fig.  103. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

FORNEY  PONY  LOCOMOTIVE, 

BY  THE 

Baldwin  Locomotive  Works,  Philadelphia,  Pa. 


Total  weight  in  working  order.  . . 36,840  lbs. 

Total  weight  on  driving-wheels 28,500  “ 

Diameter  of  driving-wheels 3 ft.  1 in. 

Diameter  of  truck-wheels 2 “ 0 

Diameter  of  main  driving-axle  journal 4£  “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels . 4 “ 6 

Total  wheel-base  of  engine 10  “ 9 “ 

Diameter  of  cylinders 10  in. 

Stroke  of  cylinders 16 

Outside  diameter  of  smallest  boiler  ring 34  “ 

Length  of  fire-box,  inside 2 “ 4 

Width  of  fire-box,  inside 3 “ 3i  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 2 “ 10 

Number  of  tubes 97 

Outside  diameter  of  tubes li  in. 

Length  of  tubes 8 ft.  0£  “ 

Grate  surface 7 sq.  ft. 

Heating  surface,  fire-box 33  “ “ 

Heating  surface,  tubes  300  “ “ 

Heating  surface,  total 333  “ “ 

Exhaust  nozzles Double. 

Size  of  steam-ports 9x1  in. 

Size  of  exhaust-ports *9xlf  “ 

Throw  of  eccentric 3^  “ 

Greatest  travel  of  valve 4f  “ 

Outside  lap  of  valve 0-f£  “ 

Smallest  inside  diameter  of  chimney 10 

Height,  top  of  rail  to  top  of  chimney 11  “ 6 “ 

Height,  top  of  rail  to  centre  of  boiler 4 “ 6 “ 

Water  capacity  of  tank 450  gals. 


BY  THE  SCHENECTADY  LOCOMOTIVE  WORKS,  SCHENECTADY, 


Different  Kinds  of  Locomotives. 


137 


Fig.  104. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

FORNEY  LOCOMOTIVE  FOR  SUBURBAN  TRAFFIC, 

BY  THE 

Schenectady  Locomotive  Works,  Schenectady,  N.  Y. 


Total  weight  in  working  order 110,000  lbs. 

Total  weight  on  driving-wheels 75,000  “ 

Diameter  of  driving-wheels 4 ft.  9 in. 

Diameter  of  truck-wheels 2 “ 6 

Diameter  of  main  driving-axle  journal 7£  “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels,  7 “ 6 

Total  wheel-base  of  engine 23  “ 7 “ 

Diameter  of  cylinders 17 

Stroke  of  cylinders 24 

Outside  diameter  of  smallest  boiler  ring 54  “ 

Length  of  fire-box,  inside 5 ft.  0T3^  “ 

Width  of  fire-box,  inside 2 “10f  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 5 “ 6 

Number  of  tubes 187 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 11  ft.  6 “ 

Grate  surface 14.3  sq.  ft. 

Heating  surface,  fire-box 127.8  “ “ 

Heating  surface,  tubes 1,116.9  “ “ 

Heating  surface,  total ....1,244.7  “ “ 

Exhaust  nozzles Single. 

Size  of  steam-ports 16  x If  in. 

Size  of  exhaust-ports 16  x 2f  “ 

Throw  of  eccentrics 5 f “ 

Greatest  travel  of  valve 5f  “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney 1 ft.  6 “ 

Height,  top  of  rail  to  top  of  chimney 14  “ 4 “ 

Height,  top  of  rail  to  centre  of  boiler 6 “ 8 “ 

Water  capacity  of  tank 1,500  gals. 

Coal  capacity 6,000  lbs. 


138 


Catechism  of  the  Locomotive, 


Fig.  105. 

FORNEV  LOCOMOTIVE,  FOR  THE  NEW  YORK  ELEVATED  RAILROAD. 

BY  THE  ROME  LOCOMOTIVE  WORKS,  ROME,  N.  Y. 


Different  Kinds  of  Locomotives. 


139 


Fig.  105. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

FORNEY  LOCOMOTIVE  FOR  THE  NEW  YORK  ELEVATED 

RAILROAD, 

BY  THE 

Rome  Locomotive  Works,  Rome,  N,  Y. 


Total  weight  in  working  order 44,350  lbs. 

Total  weight  on  driving-wheels 29,700  “ 

Diameter  of  driving-wheels 3 ft.  6 in. 

Diameter  of  main  driving-axle  journal 5f  “ 

Length  of  main  driving-axle  journal 6f  “ 

Diameter  of  truck-wheels 2 “ 6 

Distance  between  centre  of  driving-wheels 5 “ 0 

Distance  between  centres  of  truck-wheels 4 “ 8 

Total  wheel-base  of  engine 16  “ 0 

Diameter  of  cylinders 12 

Stroke  of  cylinders 16 

Outside  diameter  of  smallest  boiler  ring 3 “ 6 

Length  of  fire-box,  inside 4 “ 7T5^  “ 

Width  of  fire-box,  inside 3 “ 7 “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 2 “ Ilf  “ 

Number  of  tubes 154 

Outside  diameter  of  tubes If  in. 

Length  of  tubes 6 ft.  3f  “ 

Grate  surface 16.43  sq.ft. 

Heating  surface,  fire-box 55.77  “ “ 

Heating  surface,  tubes 375.15  “ “ 

Heating  surface,  total 430.92  “ “ 

Size  of  steam-ports 8f  x Of  in. 

Size  of  exhaust-ports 8f  x If  “ 

Throw  of  eccentrics 3f  “ 

Greatest  travel  of  valve 3f  “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney lOf  “ 

Height,  top  of  rail  to  top  of  chimney 12  “ 1 

Height,  top  of  rail  to  centre  of  boiler 5 “ 5|  “ 

Water  capacity  of  tank 600  gals. 


BY  THE  TAUNTON  LOCOMOTIVE  MANUFACTURING  COMPANY,  TAUNTON.  MASS. 


Different  Kinds  of  Locomotives.  14 1 

Fig.  106. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

LOCOMOTIVE  FOR  LOCAL  PASSENGER  SERVICE, 

BY  THE 

Taunton  Locomotive  Manufacturing  Company,  Taunton,  Mass. 


Total  weight  in  working  order 118,700  lbs. 

Total  weight  on  driving-wheels 56,300  “ 

Diameter  of  driving-wheels 5 ft.  3 in. 

Diameter  of  truck-wheels 2 “ 2 “ 

Diameter  of  main  driving-axle  journal 7-§-  “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels . 6 “ 8 “ 

Total  wheel-base  of  engine 16  “ 4 “ 

Total  wheel-base  of  engine  and  tender 34  “ 5 " 

Diameter  of  cylinders 17  “ 

Stroke  of  cylinders 20  “ 

Outside  diameter  of  smallest  boiler  ring 54  “ 

Length  of  fire-box,  inside 5 “ 0 “ 

Width  of  fire-box,  inside 2 “ lOf  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 5 “ 4 “ 

Number  of  tubes 170 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 10  “ lOf  “ 

Grate  surface 14  sq.  ft. 

Heating  surface,  fire-box 96f  “ “ 

Heating  surface,  tubes 1,097  “ “ 

Heating  surface,  total l,193f  “ “ 

Exhaust  nozzles Single. 

Size  of  steam-ports 17x1  in. 

Size  of  exhaust-ports 17x2^  “ 

Throw  of  eccentric 4f  “ 

Greatest  travel  of  valve 5 “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney 1 ft.  4 “ 

Height,  top  of  rail  to  top  of  chimney 13  “ 6 “ 

Height,  top  of  rail  to  centre  of  boiler 6 “ 8 “ 

Water  capacity  of  tank 2,200  gals. 


SIX-COUPLED  RAPID  TRANSIT  LOCOMOTIVE. 


Different  Kinds  of  Locomotives. 


Fig.  107. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

SIX-COUPLED  RAPID  TRANSIT  LOCOMOTIVE, 

BY  THE 

Brooks  Locomotive  Works,  Dunkirk,  N Y. 


Total  weight  in  working  order. 112,000  lbs. 

Total  weight  on  driving-wheels 70,000  “ 

Diameter  of  driving-wheels 4 ft.  0 in. 

Diameter  of  truck-wheels 2 “ 4 

Diameter  of  main  driving-axle  journal 7 “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels. 10  “ 0 

Total  wheel-base  of  engine 30  “ 0 “ 

Diameter  of  cylinders 16  in. 

Stroke  of  cylinders 24  “ 

Outside  diameter  of  smallest  boiler  ring 54 

Length  of  fire-box,  inside 6 “ 6 “ 

Width  of  fire-box,  inside 2 “ 10  “ 

Depth  of  fire-box,  crown-sheet  to  hand-ring 5 “ If  “ 

Number  of  tubes 186 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 9 ft.  0 “ 

Grate  surface 18f  sq.  ft. 

Heating  surface,  fire-box 97  <r  “ 

Heating  surface,  tubes 870  “ " 

Heating  surface,  total 967  “ “ 

Exhaust  nozzles Single  or  Double. 

Size  of  steam-ports 15  x If  in. 

Size  of  exhaust-ports 15  x2f  “ 

Throw  of  eccentrics 5 “ 

Greatest  travel  of  valve 5 f “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney 1 ft.  1 “ 

Height,  top  of  rail  to  top  of  chimney 13  “ 2 

Height,  top  of  rail  to  centre  of  boiler 6 “ 4f  “ 

Water  capacity  of  tank 2,000  gals. 


PY  THE  KOGERS  LOCOMOTIVE  AND  MACHINE  WORKS,  PATERSON, 


Different  Kinds  of  Locomotives. 


145 


Fig.  108. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

LOCOMOTIVE  FOR  SUBURBAN  PASSENGER  SERVICE, 

BY  THE 

Rogers  Locomotive  and  Machine  Works,  Paterson,  N.  J. 


Total  weight  in  working  order 

Total  weight  on  driving-wheels 

Diameter  of  driving-wheels 

Diameter  of  truck-wheels 

Diameter  of  main  driving-axle  journal 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels. 

Total  wheel-base  of  engine 

Diameter  of  cylinders 

Stroke  of  cylinders 

Outside  diameter  of  smallest  boiler  ring 

Length  of  fire-box,  inside 

Width  of  fire-box,  inside 

Depth  of  fire-box,  crown-sheet  to  top  of  grate j 

Number  of  tubes 

Outside  diameter  of  tubes 

Length  of  tubes 

Grate  surface 

Heating  surface,  fire-box 

Heating  surface,  tubes 

Heating  surface,  total 

Exhaust  nozzles 

Size  of  steam-ports 

Size  of  exhaust-ports 

Throw  of  eccentrics 

Greatest  travel  of  valve 

Outside  lap  of  valve 

Smallest  inside  diameter  of  chimney 

Height,  top  of  rail  to  top  of  chimney 

Height,  top  of  rail  to  centre  of  boiler 

Water  capacity  of  tank 


98,500  lbs. 
50,000  “ 

4 ft.  6 in. 
2 “ 9 “ 

6£  “ 
6 “ 3 “ 

27  “ 0 „ 

14  “ 

22  “ 


52 

5 ft.  lli 
3 “ 5 
3 “ 0 
3 “ 5f 


186 


If  in. 
7 “ lOf  “ 
20i  sq.  ft. 
77f  “ “ 
667f  “ “ 
745i  “ “ 
Double. 
14  x li  in. 
14  x 2i  “ 
5 “ 


5 “ 


Of  “ 
Hi  “ 
14  ft.  0 “ 


6 “ 10i  “ 
1,000  gals. 


BY  THE  ROGERS  LOCOMOTIVE  AND  MACHINE  WORKS,  PATERSON, 


Different  Kinds  of  Locomotives.  • 


147 


Fig.  109. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

HUDSON  DOUBLE-ENDER  LOCOMOTIVE, 

BY  THE 

Rogers  Locomotive  and  Machine  Works,  Paterson,  N.  J. 


Total  weight  in  working  order 51,100  lbs. 

Total  weight  on  driving-wheels 30,500 

Diameter  of  driving-wheels 4 ft.  Of  in. 

Diameter  of  truck-wheels 2 “ 2 “ 

Diameter  of  main  driving-axle  journal 5f  “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels,  6 “ 0 “ 

Total  wheel-base  of  engine 22  “ 1 “ 

Total  wheel-base  of  engine  and  tender 39  “ 2f  “ 

Diameter  of  cylinders 12  “ 

Stroke  of  cylinders 20  “ 

Outside  diameter  of  smallest  boiler  ring 39f  “ 

Length  of  fire-box,  inside 4 ft.  3 “ 

Width  of  fire-box,  inside 2 “ 1 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 4 “ Of  “ 

Number  of  tubes 100 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 10  ft.  2f  “ 

Grate  surface 8f  sq.  ft. 

Heating  surface,  fire-box 61  “ “ 

Heating  surface,  tubes 534f  “ “ 

Heating  surface,  total 595f  “ “ 

Exhaust  nozzles Double. 

Size  of  steam-ports - lOf  x 1T3T  in. 

Size  of  exhaust-ports lOf  x 2f 

Throw  of  eccentrics 4f  “ 

Greatest  travel  of  valve 4f  “ 

Outside  lap  of  valve 0f|  * 

Smallest  inside  diameter  of  chimney lOf  “ 

Height,  top  of  rail  to  top  of  chimney 11  ft.  4f  “ 

Height,  top  of  rail  to  centre  of  boiler 5 “ 7 

Water  capacity  of  tank 1,250  gals. 


EIGHT-WHEELED  “AMERICAN”  LOCOMOTIVE. 


Different  Kinds  of  Locomotives. 


149 


Fig.  110. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

EIGHT-WHEELED  “AMERICAN”  LOCOMOTIVE, 

BY  THE 

Hinkley  Locomotive  Company,  Boston,  Mass. 


Total  weight  in  working  order 96,000  lbs. 

Total  weight  on  driving-wheels 64,000  “ 

Diameter  of  driving-wheels 5 ft.  2 in. 

Diameter  of  truck-wheels 2 “ 6 f< 

Diameter  of  main  driving-axle  journal 7-J-  “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels,  8 “ 6 “ 

Total  wheel-base  of  engine 23  “ Of  “ 

Total  wheel-base  of  engine  and  tender 46  “ 2f  “ 

Diameter  of  cylinders 17  “ 

Stroke  of  cylinders 24  “ 

Outside  diameter  of  smallest  boiler  ring 53f  “ 

Length  of  fire-box,  inside 6 ft.  0 “ 

Width  of  fire-box,  inside 2 “ 11  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 5 “ 8 “ 

Number  of  tubes 218 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 11  ft.  6 “ 

Grate  surface 17.5  sq.  ft. 

Heating  surface,  fire-box 125  “ “ 

Heating  surface,  tubes 1,230  “ “ 

Heating  surface,  total 1,355  “ “ 

Exhaust  nozzles Single. 

Size  of  steam-ports 18  x If  in. 

Size  of  exhaust-ports 18x3  “ 

Throw  of  eccentrics 5 “ 

Greatest  travel  of  valve 5f  “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney 1 ft.  2 “ 

Height,  top  of  rail  to  top  of  chimney 14  “ If  “ 

Height,  top  of  rail  to  centre  of  boiler 6 “ 8f  “ 

Water  capacity  of  tank 3,000  gals. 


EIGHT- WHEELED  “AMERICAN”  LOCOMOTIVE, 


Different  Kinds  of  Locomotives. 


151 


Fig.  111. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

EIGHT-WHEELED  “AMERICAN”  LOCOMOTIVE, 

BY  THE 

Grant  Locomotive  Works,  Paterson,  N.  J. 


Total  weight  in  working  order 

Total  weight  on  driving-wheels 

Diameter  of  driving-wheels 

Diameter  of  truck-wheels 

Diameter  of  main  driving-axle  journal 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels . 

Total  wheel-base  of  engine 

Total  wheel-base  of  engine  and  tender 

Diameter  of  cylinders 

Stroke  of  cylinders 

Outside  diameter  of  smallest  boiler  ring 

Length  of  fire-box,  inside 

Width  of  fire-box,  inside 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 

Number  of  tubes 

Outside  diameter  of  tubes 

Length  of  tubes 

Grate  surface 

Heating  surface,  fire-box 

Heating  surface,  tubes 

Heating  surface,  total 

Exhaust  nozzles  .1 

Width  of  steam-ports 

Width  of  exhaust-ports 

Throw  of  eccentrics 

Greatest  travel  of  valve 

Outside  lap  of  valve 

Smallest  inside  diameter  of  chimney 

Height,  top  of  rail  to  top  of  chimney 

Height,  top  of  rail  to  centre  of  boiler 

Water  capacity  of  tank 


100,000  lbs. 

64,100  “ 

. 5 ft.  2 in. 
2 “ 6 “ 
n “ 

8 “ 6 “ 
23  “ 3 “ 

45  “ 71  “ 

18  “ 
24  “ 

54  “ 

6 ft.  0 “ 

2 “ 10*“ 

5 “ 6 “ 

227 
2 in. 

. 11  ft.  11  “ 
17  sq.ft. 
123  “ “ 

. 1,343  “ “ 

. 1,466  “ “ 
Double. 
11  in. 
21  “ 
51  “ 
51  “ 

1 “ 

. 1 ft.  6 “ 

. 15  “ 0 “ 

. 6 “ 71  “ 

3,600  gals. 


I 


BV  THE  HINKLEY  LOCOMOTIVE  COMPANY,  BOSTON,  MASS. 


Different  Kinds  of  Locomotives. 


153 


Fig.  112. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

MOGUL  FREIGHT  LOCOMOTIVE, 

BY  THE 

Hinkley  Locomotive  Company,  Boston,  Mass. 


Total  weight  in  working  order 104,000  lbs. 

Total  weight  on  driving-wheels 90,000 

Diameter  of  driving-wheels 4 ft.  4 J in. 

Diameter  of  truck-wheels •...'. 2 “ 6 “ 

Diameter  of  main  driving-axle  journal 7\  “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels.  15  “ 9 “ 

Total  wheel-base  of  engine 23  “ 4 „ 

Total  wheel-base  of  engine  and  tender 46  “ 5f  “ 

Diameter  of  cylinders 19  “ 

Stroke  of  cylinders 24  “ 

Outside  diameter  of  smallest  boiler  ring 53|-  “ 

Length  of  fire-box,  inside 6 ft.  0 

Width  of  fire-box,  inside 2 “ 11  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 5 “ 8 

Number  of  tubes 218 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 11  “ 6 

Grate  surface 17.5  sq.  ft. 

Heating  surface,  fire-box 125  “ “ 

Heating  surface,  tubes 1,230  “ “ 

Heating  surface,  total 1,355  “ “ 

Exhaust  nozzles Single. 

Size  of  steam-ports 18  x 1£  in. 

Size  of  exhaust-ports 18x3  “ 

Throw  of  eccentrics 5 

Greatest  travel  of  valve 5|  “ 

Outside  lap  of  valve 0|  “ 

Smallest  inside  diameter  of  chimney 1 ft.  3 “ 

Height,  top  of  rail  to  top  of  chimney 14  “ 0 “ 

Height,  top  of  rail  to  centre  of  boiler 6 “ 5 “ 

Water  capacity  of  tank 3,000  gals. 


Fig.  113. 

TEN-WHEELED  FREIGHT  LOCOMOTIVE. 


Different  Kinds  of  Locomotives. 


155 


Fig.  113. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

TEN-WHEELED  FREIGHT  LOCOMOTIVE, 

15Y  THE 

Grant  Locomotive  Works,  Paterson,  N.  J. 


Total  weight  in  working  order 90,000  lbs. 

Total  weight  on  driving-wheels 66,000  “ 

Diameter  of  driving-wheels 4 ft.  6 in. 

Diameter  of  truck-wheels ' 2 “ 2 

Diameter  of  main  driving-axle  journal 74  “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels.  13  “ 6 

Total  wheel-base  of  engine 24  “ 64  “ 

Total  wheel-base  of  engine  and  tender 44  “ 104  “ 

Diameter  of  cylinders 18  “ 

Stroke  of  cylinders 24  “ 

Outside  diameter  of  smallest  boiler  ring 52 

Length  of  fire-box,  inside 6 ft.  0 

Width  of  fire-box,  inside 2 “ 104  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 5 “ 2f  “ 

Number  of  tubes 204 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 13  ft.  2f  “ 

Grate  surface 17  sq.  ft. 

Heating  surface,  fire-box 123  “ “ 

Heating  surface,  tubes 1,359  “ " 

Heating  surface,  total 1,482  “ “ 

Exhaust  nozzles Double. 

Width  of  steam-ports If  in. 

Width  of  exhaust-ports 24  “ 

Throw  of  eccentrics 54  “ 

Greatest  travel  of  valve 54  “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney 1 ft.  6 

Height,  top  of  rail  to  top  of  chimney 14  “ 4f  “ 

Height,  top  of  rail  to  centre  of  boiler 6 “ If  “■ 

Water  capacity  of  tank 3,000  gals-. 


CONSOLIDATION  LOCOMOTIVE. 


Different  Kinds  of  Locomotives* 


157 


Fig.  114. 

DIMENSIONS,  WEIGHT,  ETC.., 

OF 

CONSOLIDATION  LOCOMOTIVE,. 

BY  THE 

Pittsburgh  Locomotive  Works,  Pittsburgh,  Pa. 


Total  weight  in  working  order 104,900  lbs* 

Total  weight  on  driving-wheels 94,150  “ 

Diameter  of  driving-wheels 4 ft.  2 in* 

Diameter  of  truck-wheels 2 “ 6 “ 

Diameter  of  main  driving-axle  journal 7 “ 

Length  of  main  driving-axle  journal 9 “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels,  14  “ 2 “ 

Total  wheel-base  of  engine 21  “ 9 

Total  wheel-base  of  engine  and  tender 47  “ lOf  “ 

Diameter  of  cylinders 20  “ 

Stroke  of  cylinders 24  “ 

Outside  diameter  of  smallest  boiler  ring 4 ft.  8 “ 

Length  of  fire-box,  inside 8 “ 6 

Width  of  fire-box,  inside 2 “10f  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 4 “ 5f  “ 

Number  of  tubes 202 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 13  ft.  2 “ 

Grate  surface 24.34  sq.ft* 

Heating  surface,  fire-box 132.00  “ “ 

Heating  surface,  tubes .1,383.00  “ “ 

Heating  surface,  total 1,515.00“  “ 

Exhaust  nozzles Double* 

Size  of  steam-ports 16  x If  in* 

Size  of  exhaust-ports 16  x 2f  “ 

Throw  of  eccentrics 5 “ 

Greatest  travel  of  valve 5 “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney 1 ft.  6 “ 

Height,  top  of  rail  to  top  of  chimney 14  “ 5f  “ 

Height,  top  of  rail  to  centre  of  boiler 6 “ 9f  “ 

Water  capacity  of  tank. * 3,000  gals.. 


TWELVE-WHEELED  LOCOMOTIVE. 


Different  Kinds  of  Locomotives. 


159 


Fig.  115. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

TWELVE-WHEELED  LOCOMOTIVE, 

BY  THE 

Schenectady  Locomotive  Works,  Schenectady,  N.  Y. 

Total  weight  in  working  order 132,000  lbs. 

Total  weight  on  driving-wheels * . 112,000  “ 

Diameter  of  driving-wheels 4 ft.  3 in. 

Diameter  of  truck-wheels 2 “ 2 “ 

Diameter  of  main  driving-axle  journal 7£  “ 

Length  of  main  driving-axle  journal “ 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels . 13  “ 9 “ 

Total  wheel-base  of  engine 23  “ 6 

Total  wheel-base  of  engine  and  tender 47  “ 10 

Diameter  of  cylinders 20 

Stroke  of  cylinders 26 

Outside  diameter  of  smallest  boiler  ring 5 “ 0 “ 

Length  of  fire-box,  inside 8 “ 8T3^  “ 

Width  of  fire-box,  inside 3 “ 6£  “ 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 4 “ 11  “ 

Number  of  tubes 262 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 12  ft.  8 “ 

Grate  surface 31  sq.ft. 

Heating  surface,  fire-box 156  “ “ 

Heating  surface,  tubes 1,726  “ “ 

Heating  surface,  total 1,882  “ “ 

Exhaust  nozzles Single. 

Size  of  steam-ports 18  x 1|-  in. 

Size  of  exhaust-ports 18  x 2f  “ 

Throw  of  eccentrics “ 

Greatest  travel  of  valve “ 

Outside  lap  of  valve 0J-  “ 

Smallest  inside  diameter  of  chimney 1 ft.  4 “ 

Height,  top  of  rail  to  top  of  chimney 14  “ 10  “ 

Height,  top  of  rail  to  centre  of  boiler 7 “ 6£  “ 

Water  capacity  of  tender  tank .# 3,400  gals. 

Note.  In  this  engine  the  first  and  third  pairs  of  driving-wheels  have  blank  tires,  so  that  the 
rigid  wheel-base  is  only  9 ft.  2 in. 


DECAPOD  LOCOMOTIVE. 


Different  Kinds  of  Locomotives. 


161 


Fig.  118. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

DECAPOD  LOCOMOTIVE, 

BY  THE 

Baldwin  Locomotive  Works,  Philadelphia,  Pa. 


Total  weight  in  working  order 148,000  lbs. 

Total  weight  on  driving-wheels 133,000  “ 

Diameter  of  driving-wheels 3 ft.  9 in. 

Diameter  of  truck-wheels 2 “ 6 

Diameter  of  main  driving-axle  journal 8 

Length  of  main  driving-axle  journal 9 

Distance  from  centre  of  front  to  centre  of  back  driving-wheels . 17  “ 0 

Total  wheel-base  of  engine 24  “ 4 

Total  wheel-base  of  engine  and  tender 49  “ 2 

Diameter  of  cylinders 22 

Stroke  of  cylinders 26 

Outside  diameter  of  smallest  boiler  ring 5 “ 8 

Length  of  fire-box,  inside 10  “ 1^ 

Width  of  fire-box,  inside 3 “ 61- 

Depth  of  fire-box,  crown-sheet  to  top  of  grate 4 “ 6^ 

Numberof  tubes 270 

Outside  diameter  of  tubes 2^  in. 

Length  of  tubes 13  “ 6 “ 

Grate  surface 36  sq.  ft. 

Heating  surface,  fire-box 162  “ “ 

Heating  surface,  tubes 2,148  “ “ 

Heating  surface,  total 2,310  “ “ 

Exhaust  nozzles Double. 

Size  of  steam-ports 16xl|-  in. 

Size  of  exhaust-ports 16x3 

Throw  of  eccentric 5 

Greatest  travel  of  valve 5f 

Outside  lap  of  valve Of 

Smallest  inside  diameter  of  chimney 1 ft.  8 

Height,  top  of  rail  to  top  of  chimney 14  “ 6 

Height  top  of  rail  to  centre  of  boiler 7 “ 3^ 

Water  capacity  of  tender  tank 3,600  gals. 


162 


Catechism  of  the  Locomotive. 


Different  Kinds  of  Locomotives. 


(68 


Fig.  117. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

TANK  LOCOMOTIVE  FOR  PASSENGER  SERVICE, 

BY  THE 

Baldwin  Locomotive  Works,  Philadelphia,  Pa. 


Total  weight 66,000  lbs. 

Diameter  of  driving-wheels 50  in. 

Diameter  of  main  driving-axle  journal 6^-  “ 

Length  of  main  driving-axle  journal 8 “ 

Spread  of  driving-wheels 7 ft.  6 “ 

Total  wheel-base 21  “ 8 “ 

Diameter  of  cylinders 15  “ 

Stroke  of  piston 22  “ 

Outside  diameter  of  smallest  boiler  ring 46  “ 

Number  of  tubes 130 

Outside  diameter  of  tubes 2 in. 

Length  of  tubes 8 ft.  6 “ 

Exhaust-nozzles Single. 

Size  of  steam-ports 13  x If  in. 

Size  of  exhaust-ports 13x2f  “ 

Throw  of  eccentrics 4f  “ 

Greatest  travel  of  valve 5 “ 

Outside  lap Of  “ 

Smallest  inside  diameter  of  chimney 13  “ 

Height,  top  of  rail  to  top  of  chimney 14  “ 

Water  capacity  of  tank 900  gals. 


164 


Catechism  of  the  Locomotive. 


LOCOMOTIVE  FOR  STREET  RAILROADS. 


Different  Kinds  of  Locomotives. 


165 


Fig.  118. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

LOCOMOTIVE  FOR  STREET  RAILROADS, 

BY  THE 

Baldwin  Locomotive  Works,  Philadelphia,  Pa. 


Total  weight 30,000  lbs. 

Diameter  of  driving-wheels 35  in. 

Diameter  of  main  driving-axle  journal 4f  “ 

Length  of  main  driving-axle  journal 6f  “ 

Spread  of  driving-wheels 4 ft.  6 “ 

Total  wheel-base 9 “ 8 

Diameter  of  cylinders 10 

Stroke  of  piston 14  “ 

Outside  diameter  of  smallest  boiler  ring 34 

Number  of  tubes 100 

Outside  diameter  of  tubes If  in. 

Length  of  tubes 6 ft.  0 “ 

Grate  surface 9 sq.  ft. 

Heating  surface,  fire-box 35  “ “ 

Heating  surface,  tubes 234  “ “ 

Heating  surface,  total.. . . 269  “ “ 

Exhaust-nozzles Single. 

Size  of  steam-ports £x7  in. 

Size  of  exhaust-ports I£x7 

Throw  of  eccentrics 2f  “ 

Greatest  travel  of  valve 3£  “ 

Outside  lap  of  valve Of  “ 

Smallest  inside  diameter  of  chimney 9 

Height,  top  of  rail  to  top  of  chimney 11  ft.  3 

Water  capacity  of  tank 400  gals. 


166 


Catechism  of  the  Locomotive. 


Fig.  119. 


STEAM  CAR  FOR  STREET  RAILROADS. 


BY  THE  BALDWIN  LOCOMOTIVE  WORKS,  PHILADELPHIA,  PA. 


Fig.  120. 

ENGINE  OF  STEAM  CAR  FOR  STREET  RAILROADS. 


BY  THE  BALDWIN  LOCOMOTIVE  WORKS,  PHILADELPHIA,  PA, 


167 


Different  Kinds  of  Locomotives. 


Figs.  119  and  120. 

DIMENSIONS,  WEIGHT,  ETC., 

OF 

STEAM  CAR  FOR  STREET  RAILROAD, 

BY  THE 

Baldwin  Locomotive  Works,  Philadelphia,  Pa. 


Total  weight  with  20  passengers 21,000  lbs. 

Diameter  of  driving-wheels 30  in. 

Diameter  of  main  driving-axle  journal 4£  “ 

Length  of  main  driving-axle  journal 6 

Spread  of  wheels 6 ft.  6 

Diameter  of  cylinders 8 “ 

Stroke  of  piston 10 

Outside  diameter  of  smallest  boiler  ring 32  “ 

Number  of  tubes 122 

Outside  diameter  of  tubes ‘ 1J  in. 

Length  of  tubes 46J  “ 

Grate  surface 26|  diam. 

Heating  surface,  fire-box 25J  in.  high. 

Heating  surface,  tubes .... 

Heating  surface,  total „ .... 

Exhaust  nozzles Single. 

Size  of  steam-ports 3 x in. 

Size  of  exhaust-ports 3x1  “ 


Throw  of  eccentrics 2 

Greatest  travel  of  valve 2. 

Outside  lap  of  valve 

Smallest  inside  diameter  of  chimney.  7 

Height,  top  of  rail  to  top  of  chimney. 

Water  capacity  of  tank 


11  ft. 
06  gals. 


CHAPTER  XII. 


LOCOMOTIVE  BOILERS. 

QUESTION  217.  What  are  the  principal  parts  or  “ organs"  of a locomo- 
tive boiler  ? 

Answer.  These  are  shown  in  figs.  121,  122,  and  123.  Fig.  121  is  a lon- 
gitudinal section ; fig.  122  a transverse  section  through  the  fire-box,  and 
fig.  123  is  a plan  of  the  grate.  The  principal  parts  or  organs  are  : 

1.  A fire-place,  or,  as  it  is  called,  a fire-box , A (fig.  121),  which  is  sur- 
rounded with  water. 

2.  A cylindrical  part,  C C,  attached  to  the  fire-box  at  one  end  and  to  a 
chamber,  B,  called  the  smoke-box,  at  the  other. 

3.  The  tubes  or  flues,  a a',  which  connect  the  fire-box  with  the  smoke- 
box  and  pass  through  the  cylindrical  part  of  the  boiler  and  are  surrounded 
with  water. 

4.  The  “smoke-stack  ” or  chimney,  D. 

Question  218.  What  is  each  of  these  parts,  or  organs , for,  and  of 
what  do  they  consist  ? 

Answer.  The  fire-box,  A,  is  the  fire-place,  and  furnishes  the  room  for 
burning  the  fuel,  and  consists  of  an  inner  and  outer  shell,  b and  c,  made  of 
boiler  plate,  with  the  space  between  the  two  filled  with  water ; a grate,  G, 
formed  of  iron  bars,  with  spaces  between  them  for  admitting  air  for  the 
combustion  of  the  fuel,  which  is  placed  on  top  of  them ; a door,  E,  called 
the  furnace-door,  for  supplying  the  grate  with  fuel ; a receptacle,  E E,  be- 
low the  grate,  to  collect  ashes,  and  therefore  called  the  ash-pan,  which  is 
supplied  with  suitable  doors  or  dampers  for  admitting  or  excluding  air 
from  the  fire. 

The  cylindrical  part,  C C,  or  waist  of  the  boiler,  as  it  is  sometimes  called, 
contains  the  greater  part  of  the  water  to  be  heated. 

The  smoke  and  products  of  combustion  are  conducted  from  the  fire-box, 
at  the  back  end,  to  the  smoke-box  at  the  front  end  of  the  boiler  by  means 
of  the  flues  or  tubes,  a a ' , which  are  usually  about  2 inches  in  diameter 
and  from  10  to  12  feet  long.  These  tubes  are  surrounded  with  water  and 
are  made  of  small  diameter  so  as  to  sub-divide  the  smoke  into  many 


J 

U. 

Q 

o| 

t§^j| 

CQ 

□ 

U ft 

£ 

0 


:> 


Fig.  121.  Longitudinal  Section  of  Locomotive  Boiler.  Scale 


170 


Catechism  of  the  Locomotive. 


small  streams  and  thus  expose  it  to  a large  radiating  surface  through 
which  the  heat  is  conducted  to  the  water. 


Fig.  122.  Transverse  Section  of  Boiler  through  Fire-Box.  Scale  J4  in.=l  ft. 


B 


Fig.  123.  Plan  of  Grate.  Scale  J4  in. 


Locomotive  Boilers. 


171 


The  chimney  of  smoke-stack  serves  partly  for  removing  into  the  open 
air  the  smoke  which  passes  through  the  flues,  and  partly  for  producing  a 
strong  draft  of  air,  which  is  indispensably  necessary  for  the  rapid  combus- 
tion of  the  fuel.  In  some  cases  the  smoke-stack  is  provided  with  appliances 
for  arresting  and  extinguishing  the  sparks  from  the  fire. 

QUESTION  219.  How  is  the  draft  produced  in  locomotive  boilers? 

Answer.  By  conducting  the  exhaust  steam  through  one  or  more  pipes 
( d , fig.  121)  from  the  cylinders  to  the  smoke-box  and  allowing  it  to  escape 
up  the  chimney  from  an  aperture  or  apertures,  e,  called  exhaust-nozzles* 
The  strong  current  of  steam  thus  produced  in  the  chimney  creates  a 
partial  vacuum  in  the  smoke-box,  by  which  the  smoke  is  sucked  into  it 
from  the  tubes  with  great  power,  and  is  then  forced  up  the  chimney  into 
the  open  air  by  the  “ blast,”  as  the  action  of  the  exhaust  steam  is  called. 

Question  220.  How  does  the  quantity  of  steam  generated  in  locomotive 
boilers  in  a given  time  compare  with  that  generated  in  the  boilers  of  station- 
ary and  marine  engines  ? 

Answer.  Locomotive  engine  boilers  must  produce  much  more  steam 
in  a given  time  in  proportion  to  their  size  than  is  required  of  the  boilers 
of  any  other  class  of  engines  (excepting,  perhaps,  those  of  steam  fire-en- 
gines), because  the  space  which  locomotive  boilers  can  occupy  and  also 
their  weight  must  be  less  in  proportion  to  their  capacity  than  that  of 
boilers  for  other  kinds  of  engines. 

QUESTION  221.  How  is  their  steam-generating  capacity  increased  above 
that  of  marine  and  stationary  boilers  ? 

Answer.  By  creating  a very  strong  draft  of  air  through  the  fire,  by 
means  of  the  blast,  and  then  passing  the  smoke  and  heated  air  through 
the  tubes.  By  this  means  the  smoke  and  hot  air  are  divided  into  many 
small  streams  or  currents,  which  are  exposed  to  the  inside  surface  of  the 
tubes,  and  the  heat  is  thus  imparted  to  the  water  which  surrounds  the 
tubes. 

Question  222.  How  is  the  action  of  the  exhaust  steam  in  producing  a 
draft  in  the  chimney  explained  ? 

Answer.  The  exhaust  steam  escapes  from  the  cylinders  through  con- 
tracted openings  or  exhaust-nozzles,  e,  which  point  directly  up  the  centre 
of  the  chimney.  The  exhaust  steam  escapes  from  this  orifice  with  great 
velocity,  and  expands  as  it  rises,  so  that  it  fills  the  chimney,  D.  It  thus 
acts  somewhat  like  a plunger  or  piston  forced  violently  up  the  chimney, 
and  pushes  up  the  air  above  it,  and  carries  that  which  surrounds  it  along 


* The  term  blast-orifice  is  also  often  used  to  designate  these  parts  of  locomotives. 


172 


Catechism  of  the  Locomotive. 


with  it.  They  finally  escape  into  the  open  air,  thus  leaving  a partial 
vacuum  behind  in  the  smoke-box.  The  external  pressure  of  the  atmos- 
phere then  forces  in  air  through  any  and  every  opening  in  the  smoke- 
box,  to  take  the  place  of  that  already  drawn  out  or  exhausted  from  it.  As 
the  only  inlet  is  through  the  tubes,  to  which  the  gases  of  combustion 
have  free  access  from  the  fire-box,  and  as  the  external  air  can  only  pass 
through  the  fire-grate,  and  through  the  burning  fuel,  to  reach  the  fire-box, 
there  is  a constant  draft  of  air  through  the  grate  as  long  as  the  waste 
steam  escapes  from  the  blast-pipe  and  up  the  chimney.  It  is  thus  that, 
within  certain  limits,  the  more  the  steam  that  is  required,  the  more  the 
steam  that  is  produced ; for  all  the  steam  used  in  the  engine  draws  in  the 
air  in  its  final  escape,  to  excite  the  fire  to  generate  more  steam.*  Some- 
times one  blast-orifice  is  used  for  each  cylinder ; in  other  cases  the  exhaust 
steam  from  each  cylinder  escapes  through  the  same  orifice. 

Question  228.  How  much  water  is  it  necessary  to  evaporate  in  order 
to  furnish  the  steam  required  to  run  an  ordinary  train  at  its  usual  speed? 

Answer.  An  ordinary  “American”  locomotive,  weighing  80,000  lbs. 
and  with  cylinders  of  18  inches  diameter  and  24  inches  stroke,  will  evapor- 
ate from  7,500  to  15,000  lbs.  of  water  per  hour. 

Question  224.  How  much,  water  will  a pound  of  coal  evaporate  in 
ordinary  practice  ? 

Answer.  The  quantity  of  water  which  is  converted  into  steam  by  a 
pound  of  coal  varies  very  materially  with  the  quality  of  the  coal  and  the 
construction  and  condition  of  the  boiler ; but  from  6 to  8 lbs.  of  water  per 
pound  of  coal  is  about  the  average  performance  of  ordinary  locomotives. 
It  is,  therefore,  necessary  at  times  to  burn  2,500  lbs.  of  coal  per  hour  in 
order  to  generate  the  quantity  of  steam  required  by  such  an  engine. 

QUESTION  225.  How  large  a grate  is  needed  to  burn  this  quantity  of 
coal? 

Answer.  The  maximum  rate  of  combustion  may  be  taken  at  about  125 
lbs.  of  coal  on  each  square  foot  of  grate  surface  per  hour,  so  that  to  burn 
2,500  lbs.  we  need  a grate  with  about  20  square  feet  of  surface. 

Question  226.  How  much  heating  surface  is  needed  for  a given  size  of 
grate  ? 

Answer.  In  common  practice  about  50  to  75  square  feet  of  heating 
surface  are  given  for  each  square  foot  of  grate.  There  are,  however,  no 
reasons  for  the  proportions  of  either  grate  or  heating  surface  which  are 
given,  excepting  that  it  has  been  found  that  they  give  good  results  in 


* Colburn’s  “ Locomotive  Engineering.” 


Locomotive  Boilers. 


178 


ordinary  working.  The  proportion  of  grate  to  heating  surface  is  governed 
to  a very  great  extent  by  the  kind  of  fuel  used.  Anthracite  coal  and  the 
poorer  qualities  of  fuel  require  larger  grates  than  good  bituminous  coal  or 
wood.  It  is,  however,  quite  certain  that  the  larger  a boiler  is,  and  the 
greater  its  heating  surface  in  proportion  to  the  steam  it  must  generate, 
other  things  being  equal,  the  more  economical  will  it  be  in  its  consump- 
tion of  fuel,  or,  in  other  words,  the  more  water  will  it  evaporate  per  pound 
of  coal. 

QUESTION  227.  Why  is  it  necessary  to  use  small  tubes  or  flues  in  order 
to  have  the  required  amount  of  heating  surface  ? 

Answer.  Because  there  is  a great  deal  more  surface  in  a small  tube  of 
a given  length,  in  proportion  to  the  space  it  occupies,  than  in  a large  one. 
Thus  a tube  2 inches  in  diameter  and  12  feet  long  has  6.28  square  feet  of 
surface,  and  one  4 inches  in  diameter  has  12.56  square  inches,  or  just 
double  the  quantity.  But  the  4-inch  tube  occupies  four  times  as  much 
space  as  the  other,  as  it  is  twice  as  high  and  twice  as  wide.  Therefore,  in 
proportion  to  the  space  it  occupies,  the  tube  which  is  2 inches  in  diameter 
has  twice  as  much  surface  as  the  larger  one.  If  we  compare  a 2-inch  with 
an  8-inch  tube,  we  will  find  that  the  former  has  four  times  as  much  sur- 
face, in  proportion  to  its  size,  as  the  8-inch  tube.  As  the  size  and  weight 
of  locomotive  boilers  are  limited,  it  is  therefore  necessary,  in  order  to  get 
the  requisite  heating  surface  in  the  space  to  which  we  are  confined,  to  use 
tubes  of  small  diameter. 

Small  tubes  also  have  the  advantage  that  they  may  be  made  of  thinner 
material,  and  yet  have  the  same  strength  to  resist  a bursting  pressure  from 
within,  or  a collapsing  pressure  from  without,  as  larger  tubes  made  of 
thicker  metal.  The  advantage  of  thin  tubes  is,  that  the  heat  inside  of 
them  is  conducted  to  the  water  outside  more  rapidly  than  it  would  be 
through  thicker  metal,  which  is  important  when  combustion  is  as  rapid  as 
it  is  in  locomotive  boilers. 

The  reason  tubes  of  smaller  diameter  than  2 inches  are  not  ordinarily 
used  is  because»they  are  then  liable  to  become  stopped  up  with  cinders 
and  pieces  of  unconsumed  fuel. 

Question  228.  How  is  the  fire-box  of  a locomotive  constructed? 

Answer.  It  usually  consists  of  a rectangular  box  (A,  figs.  121,  122  and 
123,)  about  3 feet  wide,*  and,  for  the  size  of  engine  we  have  selected  as  an 
example,  about  6 or  6^  feet  long  inside.  This  box  is  composed  of  either 

* The  width  is  dependent  upon  the  distance  between  the  rails,  or  gauge  of  the  road,  as  it  is 
called.  The  above  size  is  for  a 4 ft.  in.  gauge. 


174 


Catechism  of  the  Locomotive. 


iron  or  steel  plates,  c c,*  which,  excepting  on  the  front  side,  are  from  T5^  to 
f inch  thick.  These  plates  form  the  inside  shell  of  the  fire-box,  which  is 
surrounded  by  an  outside  shell,  b b,  of  either  iron  or  steel  plates,  of  about 
the  same  thickness  as  those  composing  the  inside,  and,  as  already  ex- 
plained, it  is  so  much  larger  than  the  inside  that  there  is  a space,  called 
the  water-space , from  2%  to  4-|  inches  wide,  on  all  the  sides  of  the  fire-box 
between  the  inner  and  outer  plates. 

The  top,/ /,  of  the  inside  shell,  which  is  called  the  crown-sheet  or  crown- 
plate , is  usually  flat,  whereas  the  outside  shell  is  generally  arched,  as  shown 
in  figs.  122  and  96.  To  the  front  plate,  a'  a\  of  the  inside  shell,  the  tubes, 
a a',  a a',  are  attached.  For  this  reason  its  thickness  is  usually  made  greater 
than  that  of  the  other  plates,  and  is  usually  from  f to  f inch.  The  edges 
of  one  of  the  plates  at  each  corner  of  the  fire-box,  where  they  are  united 
together,  as  shown  at  g g,  in  fig.  123,  are  bent  at  right  angles,  and  the 
other  is  fastened  to  it  with  rivets,  not  shown  in  the  engraving,  from  f to  f 
inch  in  diameter. 

The  inside  and  the  outside  shells  of  the  fire-box  are  united  to  each 
other  by  a wrought-iron  bar  or  ring , h h,  fig.  121,  called  a mud-ring , which 
completely  surrounds  the  inner  shell  and  closes  the  water-space  between 
the  two  shells.  This  bar  is  bent  and  welded  to  the  proper  form  to  extend 
around  the  bottom  of  the  inside  fire-box,  and  it  is  riveted  to  both  shells. 
The  water  in  the  water-space  is  in  free  communication  with  the  rest  of  the 
water  in  the  boiler,  and  thus  the  flat  sides  of  the  respective  shells  of  the 
fire-box  are  exposed  to  the  full  pressure  of  the  steam,  which  tends  to  burst 
the  outside  shell  and  collapse  the  inside  one.  These  flat  sides,  by  them- 
selves, would  be  unable  to  resist  the  strain  upon  them,  but  as  the  strain 
upon  the  respective  fire-boxes  is  in  opposite  directions,  and  necessarily 
equal  for  equal  areas  of  surface,  tie-bolts,  / i,  fig.  121,  or,  as  they  are  called, 
stay-bolts , which  are  from  f to  1 inch  in  diameter,  and  have  a screw  cut 
in  their  whole  length,  are  screwed  through  the  plates  at  frequent  intervals, 
usually  from  4 to  4\  inches  apart,  so  as  to  connect  the  inner  and  the  outer 
plates  of  the  fire-box  securely  together,  the  ends  of  the  stay-bolts  being 
also  riveted  or  spread  out  by  hammering  so  as  still  further  to  increase 
their  holding  power.  These  bolts,  owing  to  the  expansion  and  contraction 
of  the  boiler  and  other  strains  to  which  they  are  subjected,  very  frequently 
break,  and  if  they  are  made  of  solid  bars  of  metal  there  is  no  way  of  dis- 
covering with  certainty  whether  they  are  in  good  condition  or  not  without 
taking  the  boiler  to  pieces.  They  should  therefore  be  made  of  the  best 


* The  inside  plates  are  sometimes  made  of  copper. 


Locomotive  Boilers. 


175 


quality  of  wrought  iron,  brass,  or  copper,  and  should  be  made  tubular  or 
have  a hole  drilled  into  one  end,  as  shown  at  a , fig.  124,  and  extending 
into  the  bolt  a distance  greater  than  the  thickness  of  the  place  into  which 
it  is  screwed,  so  that  if  the  bolt  breaks  the  water  will  escape  at  the  fracture 


into  the  hole,  and  the  leak  will  thus  indicate  the  defect  and  danger.  The 
latter  is  much  greater  from  this  cause  than  is  usually  supposed,  and  it  is 
not  unusual  to  find  in  taking  a boiler  to  pieces  that  a large  number  of  the 
stay-bolts  are  broken.  Experience  shows,  too,  that  when  stay-bolts  break, 
the  fracture  nearly  always  occurs  next  to  the  outside  plate,  so  that  if  holes 
are  drilled  in  the  outer  ends  of  the  bolts  they  will,  in  nearly  all  cases, 
show  when  a bolt  is  broken. 

QUESTION  229.  How  can  the  strain  on  the  fiat  surface  of  a boiler  between 
the  stay-bolts  be  calculated ? 


Fig.  125.  Arrangement  of  Stay-Bolts.  Scale  *4  in.=l  in. 

Answer.  By  multiplying  the  area  in  inches  between  adjacent 
STAY-BOLTS  by  the  pressure.  The  reason  for  this  is,  that  each  stay- 
bolt  must  sustain  the  pressure  on  a part  of  the  plate  to  which  it  is  attached. 
Thus,  in  fig.  125,  it  is  plain  that  the  bolt,  s,  must  sustain  the  pressure  on 
one-half  of  that  part  of  the  plate  between  it  and  the  bolts,  v t w u,  around 


176 


Catechism  of  the  Locomotive. 


it,  or  the  pressure  on  the  square,  a b d c,  whose  sides  are  equal  to  the  dis- 
tance (4  inches)  between  the  centres  of  the  bolts.  With  a pressure  of  150 
lbs.  per  square  inch,  the  calculation  would  therefore  be  : 4 x4  x 150=2,400 
lbs.  on  each  bolt. 

Stay-bolts  should  never  be  subjected  to  a strain  of  more  than  or  T\- 
of  their  breaking  strength. 

Question  230.  How  do  stay-bolts  often  fail  without  breaking? 

Answer.  By  tearing  or  stripping  the  thread  of  the  bolt,  or  that  in  the 
plate,  but  oftener  perhaps  by  the  stretching  of  the  plates  around  the  holes. 
With  a heavy  pressure,  the  tendency  of  the  plates  between  the  holes, 
especially  if  they  are  heated  very  hot,  is  to  “ bulge”  outward,  and  thus 
stretch  the  hole  in  every  direction  until  it  is  so  large  that  the  bolt  is  drawn 
out  without  much  injury  to  the  screw-thread. 

Question  231.  How  is  the  flat-top  or  crown-sheet  strengthened? 

Answer.  Usually  the  crown-sheet  is  strengthened  by  a series  of  iron 
bars  (H  H,  figs.  121  and  122),  called  crown-bars,  placed  on  edge,  and  of 
considerable  depth,  which  are  firmly  fastened  to  it  by  rivets  or  bolts.  The 
crown-sheet  can  therefore  only  be  crushed  downward  by  bending  these 
bars,  which  are  of  great  strength.  They  usually  extend  crosswise  of  the 
length  of  the  fire-box,  but  are  sometimes  placed  lengthwise.  These 
bars  bear  on  the  fire-box  at  each  end  only,  as  shown  in  fig.  122,  and  are 
usually  made  with  projections,  j j,  which  rest  on  the  edges  of  the  side 
plates.  Iron  rings  or  washers  are  interposed  between  the  plate  and  the 
bars  at  the  points  where  the  bolts  or  rivets  which  secure  the  rivets  pass 
through.  This  permits  the  water  to  circulate  under  the  bars,  and  prevents 
the  crown-sheet  from  being  burned  or  over-heated,  as  it  would  be  if  the 
water  were  excluded  from  the  whole  under-surface  of  the  crown-bars.* 
The  crown-bars  are  also  connected  to  the  outer  shell  and  the  dome  by 
braces,  k k. 

Crown-sheets  are  sometimes  supported  by  stay-bolts,  which  are  screwed 
into  it  and  the  outer  shell  of  the  boiler,  as  shown  in  figs.  126  and  127.  A 
difficulty  with  this  form  of  construction  is  that  to  resist  the  strains  pro- 
duced by  the  steam  pressure  on  the  crown-sheet  the  bolts  should  be  placed 
at  right  angles  to  its  surface,  and  to  resist  the  pressure  against  the  inner 
side  of  the  shell  of  the  boiler  they  should  be  radial  to  its  cylindrical  form. 
As  it  is  impossible  to  locate  them  so  as  to  be  both  radial  to  the  shell  and 
at  right  angles  to  the  crown-sheet,  all  that  can  be  done  is  to  make  as  close 
an  approximation  to  each  position  as  is  possible.  Under  these  conditions 


* Colburn’s  “ Locomotive  Engineering.” 


Locomotive  Boilers. 


177 


it  is  difficult  to  know  how  much  pressure  the  stay-bolts  bear,  and  conse- 
quently the  strains  to  which  they  are  subjected  are  liable  to  be  excessive. 

Question  232.  Is  there  any  form  of  construction  which  obviates  the 
difficulty  of  staying  crown-sheets  which  has  been  pointed  out  ? 

Answer.  Yes.  In  what  is  known  as  the  Belpaire  fire-box  both  the 
crown-sheet  and  the  shell  of  the  boiler  over  it  are  made  flat,  as  shown  in 
figs.  128  and  129,  which  show  longitudinal  and  transverse  sections  of  this 


Radial  Stays.  Scale  J4  in.=l  ft. 

form  of  fire-box.  These  plates  are  stayed  with  screw-bolts,  b b b,  at  right 
angles  to  the  plates.  The  sides,  which  are  also  flat,  are  stayed  with  rods, 
r r,  r r,  which  pass  through  both  the  sides. 

This  form  of  boiler  also  has  the  advantage  that  the  flat  plates  have  more 
or  less  flexibility.  In  a boiler  like  that  shown  in  figs.  122  or  127,  if  the 
inside  plates  of  a fire-box  become  heated  while  the  outside  plate  remains 
cold,  they  expand  and  push  the  top  upward.  This  strain  is  transmitted 
to  the  outside  shell,  above  the  fire-box,  by  the  braces  or  stay-bolts,  and 
as  the  circular  form  of  the  centre  shell  gives  it  great  rigidity,  the  parts 
must  be  severely  strained.  In  a Belpaire  fire-box  the  flat  plates  above  it 
can  spring  or  bend,  and  they  thus  allow  the  inside  plates  to  expand  with- 
out injury  to  the  other  parts. 


178 


Catechism  of  the  Locomotive. 


The  crown-sheets  of  fire-boxes  should  be  made  to  slope  downward  from 
the  front  end  towards  the  back,  so  as  to  be  several  inches  lower  behind 
than  in  front,  so  that  in  case  the  water  in  the  boiler  is  allowed  to  get  low, 
only  the  front  part  of  the  crown-sheet  will  be  uncovered,  and  be  liable  to 
be  injured  by  exposure  to  the  heat  below  it. 


Scale  34  in.=l  ft.  View  of  Belpaine  Fire-Box. 

Scale  J4  in.=l  ft. 

Question  233.  How  are  the  ends  or  heads  of  boilers  strengthened? 

Answer.  Usually  diagonal  stays  or  braces,  s s s,  figs.  121  and  126,  are 
arranged  with  one  of  their  ends  attached  to  the  end  or  head  of  the  boiler, 
and  the  other  fastened  to  its  outside  shell. 

Question  234.  What  precaution  should  be  taken  in  the  design  and  con- 
struction of  stays  or  braces  like  those  which  are  used  for  strengthening  the 
ends  or  heads  of  boilers  and  supporting  the  crown-bars  ? 

Answer.  Great  care  should  be  taken  to  make  the  parts  by  which  the 
stays  are  fastened  as  strong  as  the  main  part  of  the  bar  which  forms  the 
brace.  The  principle  that  the  greatest  strength  of  any  part  of  a structure 
is  only  that  of  its  weakest  part  applies  with  especial  force  to  boiler-stays. 
Often  the  grossest  carelessness  and  ignorance  is  shown  in  designing  and 
constructing  these  parts.  The  eyes  and  the  pins  or  keys  by  which  they  are 
fastened  are  often  made  so  that  they  are  much  weaker  than  the  body  of'*' 
the  bar,  and  the  riveted  attachments  to  the  boiler-plates  often  have  only 
a small  percentage  of  the  strength  of  the  main  part  of  the  brace  or  stay. 

Question  235.  What  other  method  of  staying  boiler-heads  is  sometimes 
used? 


% 


Locomotive  Boilers.  179 

Answer.  What  are  called  “gusset  stays  ” are  used  a great  deal  in  Eu- 
ropean locomotives.  These  consist  of  triangular  pieces  of  boiler-plate,  A , 
figs.  130  and  131,  which  are  fastened  to  the  boiler-head,  B,  and  to  the 


shell,  D,  by  angle-irons,  C and  C,  which  are  riveted  to  the  head  and  to  the 
shell.  The  plate,  A,  is  placed  between  the  angle-irons  with  rivets  through 
all  three,  as  shown  in  fig.  131.  Stays  of  this  kind  are  often  used  for  Bel- 
paire  fire-boxes,  an  example  of  which  is  shown  in  fig.  128. 

Question  236.  How  are  the  grates  constructed? 

Answer.  They  are  generally  made  of  cast-iron  bars,  and  for  burning 
coal  are  usually  arranged  so  that  the  fire  can  be  shaken  by  moving  the 
bars.  Their  construction  will  be  more  fully  explained  in  chapter  XIII. 
For  burning  anthracite  coal,  the  grates  are  sometimes  made  of  wrought- 
iron  tubes,  inside  of  which  a current  of  water  circulates  to  prevent  them 
from  being  overheated. 

Question  237.  How  are  cinders  and  burning  coals  which  fall  through 
the  grate  prevented from  falling  upon  the  road? 

Answer.  By  attaching  a sheet-iron  receptacle  or  ash-pan  ( E E,  figs.  121 
and  122),  as  it  is  called,  under  the  grate,  which  is  thus  completely  enclosed 
from  the  outside  air.  As  it  is  often  important  when  the  engine  is  stand- 
ing still  to  prevent  any  access  of  air  to  the  fire-box,  the  ash-pan  is  made 
to  fit  tightly  to  the  fire-box,  so  that  air  can  be  excluded  from  the  grate. 
Suitable  doors,  or  dampers,  as  they  are  called,  are  placed  in  front  and 
behind,  and  sometimes  on  the  sides,  which  can  be  opened  or  closed  to 
admit  or  shut  out  air  as  may  be  needed. 

Question  238.  How  are  the  tubes  or  flues  of  a locomotive  arranged? 

Answer.  They  are  fastened  into  accurately  drilled  holes  in  a plate, 
called  a tube-plate  or  tube-sheet  (« a a,  figs.  121  and  122),  which  forms  the 


180 


Catechism  of  the  Locomotive. 


front  of  the  fire-box,  and  in  similar  holes  in  another  plate  ( a ' a',  fig.  121), 
which  forms  the  front  end  of  the  cylindrical  part  of  the  boiler.  They  thus 
connect  the  fire-box  with  the  smoke-box.  The  tubes  are  arranged  so  that 
each  one  will  have  a space  of  from  f to  ^ inch  between  it  and  those  next 


e 


Arrangement  of  Tubes.  Scale  in.— 1 in. 


to  it.  The  position  of  the  holes  for  the  tubes  in  relation  to  each  other  is 
determined  by  describing  from  the  centre  of  one  tube  ( o , fig.  132),  a circle 
with  a radius,  o k,  equal  to  the  sum  of  the  outside  diameter  of  the  tubes 
and  the  distance  which  they  are  intended  to  be  apart,  and  then  subdjvid- 


Locomotive  Boilers. 


181 


ing  this  circle  with  its  radius  into  six  parts,  k r,  r s,  s /,  / g,  g p and  p k. 
Each  point  of  subdivision  and  also  the  centre,  o,  of  the  circle  will  be  a 
centre  of  a tube.  By  laying  them  off  from  these  centres,  it  will  be  found 
that  the  least  distances,  a b,  c d,  between  adjoining  tubes  will  be  the  same 
between  all  of  them.  By  describing  circles  from  the  centres  of  the  out- 
side tubes  and  subdividing  the  circles  as  before,  the  position  of  other  tubes 
will  be  determined  around  those  first  laid  down.  This  can,  of  course,  be 
carried  out  indefinitely. 

A difference  in  the  arrangement  of  the  tubes  will  be  observed  by  com- 
paring figs.  132  with  133.  If,  when  we  subdivide  the  first  circle  shown  in 
fig.  132,  instead  of  commencing  from  the  intersection  of  a vertical  line,  kl, 


Fig.  134. 


Fig.  135. 


Figs.  136,  137. 

Prosser’s  Tube  Expander.  Scale  lJ4in.=l  in. 

drawn  through  the  centre,  o,  we  begin  from  a horizontal  line,  h i,  as  shown 
in  fig.  133,  then  in  the  former  case  the  tubes  will  be  in  vertical  rows , and 
in  the  latter  in  horizontal  rows.  It  is  apparent  from  the  figures  and  as 
shown  by  the  arrows  that  the  water  can  circulate  in  ascending  currents 
more  freely  when  tubes  are  arranged  in  vertical  rows  than  when  they  are 
arranged  horizontally. 


182 


Catechism  of  the  Locomotive. 


Question  239.  How  are  the  tubes  fastened  and  made  water-tight  in 
the  tube  sheets  ? 

Answer.  They  are  inserted  into  the  holes  drilled  to  receive  them,  and 
the  ends  are  allowed  to  project  about  a quarter  of  an  inch  beyond  the  tube- 
sheets.  A tool,  or  “ tube  expander as  it  is  called,  is  then  inserted  into 
the^end  of  the  tube  and  it  is  expanded  so  that  it  completely  fills  the  hole 
.in  the  tube-plate.  A number  of  different  kinds  of  tools  have  been  devised 
for  expanding  tubes  in  the  tube-plates  and  making  a shoulder  on  each 
side  of  the  plate  so  as  to  keep  the  tubes  water-tight.  Figs.  134-137 
represent  Prosser’s  expander.  When  this. is  used  a tapered  plug,  fig.  134,  is 
first  driven  into  the  tube  to  expand  it  so  that  it  will  fill  the  hole.  Fig. 
135  represents  a perspective  view,  and  figs.  136  and  137  side  and  end  eleva- 
tions of  the  “spring  expander.”  This  maybe  called  an  expanding  plug 
composed  of  eight  or  more  sector-shaped  pieces,  abode  f g and  h,  which 
are  held  together  by  an  open  steel  spring-ring  or  clasp,  s,  which  embraces 


Fig.  138.  Section  of  End  of  Tube  with  Copper  Ferrule.  Scale  *4  in.=l  in. 


them  as  shown  in  figs.  135-137.  The  inner  portion  of  the  sectors  is  cut 
away  so  as  to  leave  a hole,  C,  fig.  135  and  136,  in  the  middle  of  the  plug. 
When  the  sections  are  drawn  together  the  plug  is  inserted  into  the  mouth 
of  the  tube,  and  a tapered  plug,  p p,  fig.  135,  is  then  driven  into  the 
hole,  C.  The  spring-ring  or  clasp,  s,  permits  the  sectors  to  separate  when 
the  tapered  plug  is  driven  into  the  opening  in  the  centre  of  the  cluster  of 
sectors.  Each  of  the  sectors  ha£  a projection,  j k l m,  where  it  comes  in 
contact  with  the  outer  edge  of  the  tube,  and  another  just  inside  of  the 
tube-plate.  These  projections  form  a ridge,  abed , fig.  135,  and  another, 
j k l m,  on  the  plug.  When  the  tapered  plug  or  mandrel  is  driven  into 
the  central  opening  the  sectors  are  forced  apart,  and  they  thus  expand  tb 
tube  and  at  the  same  time  their  projections  form  a ridge  in  the  tu 
around  the  inner  and  outer  edges  of  the  hole  in  the  plate,  as  shown  at  c c, 


Locomotive  Boilers. 


188 


fig.  138.  By  slightly  turning  the  expander  each  time  the  mandrel  is 
driven  in,  and  repeating  the  process,  the  tubes  can  be  made  perfectly 
water-tight.  In  many  cases,  after  the  tubes  are  expanded  with  the  tool 
described,  the  outer  edge  is  turned  over  still  more  with  what  is  called  a 
thumb-tool , figs.  189  and  140,  probably  from  its  resemblance  in  form  to  a 
man’s  thumb.  By  placing  the  curved  shoulder,  a,  on  the  end, 

139,  of  the  tube  it  is  turned  over,  somewhat  in  the  form  showr 
graving,  by  repeated  blows  of  a hammer  on  the  end  of  the 


Fig.  140.  Caulker’s  Thumb  Tool.  Scale  J4in.=l  i 

Fig.  141  represents  Dudgeon’s  roller  expander.  This  maTOaejiesci 
as  a hollow  plug  which  has  three  rollers,  which  are  containeanPcSvities 
in  the  plug  in  which  they  can  revolve,  and  in  which  they  can  also  move  a 
short  distance  radially — that  is,  from  the  centre  of  the  plug  outward. 
When  the  expander  is  inserted  into  the  end  of  the  tube  a tapered  man- 
drel, fig.  141,  is  driven  into  the  central  opening,  and  the  plug  then  bears 


Fig.  141.  Dudgeon’s  Roller  Tube  Expander. 


against  the  rollers  and  forces  them  outward  against  the  tubes.  A crank 
handle  is  then  attached  to  the  end  of  the  mandrel,  and  is  turned  around, 
which  causes  the  rollers  to  revolve  on  their  own  axes.  This  also  causes 
the  hollow  plug  to  revolve  around  its  axis.  The  two  thus  have  a sort  of 
sun  and  planet  motion  in  relation  to  each  other.  .As  the  rollers  bear  hard 
against  the  tube,  the  effect  is  to  elongate  it  circumferentially,  and  thus 
enlarge  it  so  as  to  completely  fill  the  opening  in  the  tube-plate. 


184 


Catechism  of  the  Locomotive. 


There  are  other  forms  of  tube-expanders,  but  those  described  are  more 
generally  used  than  any  others. 

Copper  ferrules,  represented  by  the  black  shading,  a a,  fig.  138,  are  also 
much  used  now  on  the  outside  of  locomotive  tubes,  and  it  is  said  that 


Fig-.  142.  Section  of  End  of  Tube  with  Inside  Ferrule.  Scale  *4  in. =1  ft. 


with  them  the  joints  can  be  kept  tight  much  easier  than  without.  By 
turning  over  the  outside  edge  of  the  tube,  as  shown  in  fig.  138,  it  not 
only  protects  the  copper  ferrule,  but,  as  the  tubes  must  act  as  braces  to 
sustain,  the  pressure  of  steam  in  the  flat  tube-sheets,  it  gives  the  joints  the 
requisite  strength  for  resisting  such  strains. 

Cast  iron  or  steel  ferrules,  which  are  made  tapered  and  driven  into  the 
mouths  of  the  tubes,  as  shown  in  fig.  142,  are  also  used  in  some  cases. 
These  are  simply  driven  into  the  tube  after  it  has  been  expanded. 

Question  240.  How  can  the  strain  on  the  cylindrical  part  of  a boiler 
be  calculated  ? 

Answer.  By  multiplying  its  diameter  in  inches  by  its  length 

IN  INCHES  AND  ITS  PRODUCT  BY  THE  STEAM  PRESSURE  PER  SQUARE 
inch.  Thus,  for  a boiler  48  inches  in  diameter  and  10  feet  long  with  100 
lbs.  pressure  the  calculation  would  be  48  x 120  x 100=576,000  lbs. 

Question  241.  Why  do  we  multiply  the  diameter , instead  of  the  cir- 
cumference, by  the  length , to  get  the  strain  on  the  cylindrical  part  ? 

Answer.  The  reason  for  multiplying  by  the  diameter  instead  of  by  the 
circumference  is  because  only  a portion  of  the  pressure  on  the  inside  sur- 
face of  the  boiler  exerts  a force  to  burst  the  shell  at  any  one  point.  Thus, 
supposing  the  diagram,  fig.  143,  to  represent  a section  of  a boiler,  if  we 
have  a force  acting  on  the  shell  in  the  direction  of  the  line,  a b,  at  the 
point,  b , where  it  is  exerted  against  the  shell  of  the  boiler,  it  may  be 
resolved  into  two  forces,  one  acting  in  the  direction,  b e,  and  tending  to 
tear  the  boiler  apart  on  the  line,  c d,  and  the  other  acting  in  the  direction, 
f b,  to  tear  it  apart  on  the  line,  hg.  It  is  so  with  all  pressure  inside  the 


Locomotive  Boilers. 


185 


boiler,  excepting  that,  say  a h , which  acts  exactly  at  right  angles  to  the 
line  of  rupture,  c d ; it  may  all  be  resolved  into  two  forces,  only  one  of  which 
tends  to  tear  the  boiler  apart  at  one  point.  It  is,  therefore,  only  a part  of 
the  pressure  on  the  circumference  which  tends  to  burst  the  boiler  at  a 
given  place,  and  that  part  is  equivalent  to  the  pressure  on  a surface  whose 
width  is  equal  to  the  diameter  and  not  the  circumference. 


h 


Fig.  143.  Fig.  144. 

Diagram  Showing  Strain  in  Boiler.  Diagram  Showing  Pressure  in  Boiler. 


Fig.  145.  Fig.  146. 

Diagrams  Showing  Pressure  and  Strain  in  Boiler.  Scale  in.—l  ft. 


This  may  be  difficult  for  those  to  understand  who  are  not  familiar  with 
the  principle  of  the  “resolution  of  forces,”  which  was  explained  in  Chapter 
II ; but  it  may  be  made  clear  in  another  way. 

Let  it  be  supposed  that  we  have  a boiler,  a b , fig.  144,  made  in  two 


186 


Catechism  of  the  Locomotive. 


halves  and  bolted  together  at  a and  b by  flanges.  It  is  evident  that  it  we 
brought  a pressure  against  the  inside  of  the  flanges  in  the  direction  of  the 
darts,  c and  d,  such  a pressure  would  not  have  a tendency  to  tear  apart 
the  bolts,  a and  b,  by  which  the  two  halves  of  the  boiler  are  fastened 
together.  Some  distortion  of  the  boiler  might,  in  fact,  take  place  if,  for 
example,  we  put  a jack-screw  inside  and  forced  the  flanges,  a and  b , out- 
ward as  indicated  by  the  darts,  c d,  without  subjecting  the  bolts  to  a ten- 
sile strain.  We  see,  therefore,  that  the  forces  acting  in  the  direction,  c 
and  d,  have  no  tendency  to  tear  the  bolts  at  a and  b asunder,  but  it  is 
only  such  forces  as  e f and  g which  act  at  right  angles  to  the  diameter,  c 
d , that  exert  a strain  on  the  flanges. 

That  this  force  is  equivalent  to  a pressure  on  a surface  with  a width 
equal  to  the  diameter  will  be  apparent  if  we  suppose  that  we  have  a boiler, 
a b,  fig.  145,  and  that  each  half,  C and  D,  is  nearly  filled  with  some  sub- 
stance, say  wood  or  cement,  which  is  fitted  so  tight  that  no  steam  can  get 
between  it  and  the  shell  of  the  boiler.  It  will  be  apparent  that  if  we  ad- 
mits team  into  the  space,  f g,  the  force  exerted  on  the  bolts,  a and  b,  is 
that  due  to  the  pressure  on  the  surface  of  the  wood  or  cement  exposed  to 
the  steam  whose  width  is  equal  to  the  diameter  of  the  boiler.  It  may  be 
said,  though,  that  if  this  substance  were  elastic,  like  india-rubber,  the 
effect  of  the  steam  would  be  different. 

But  even  if  it  were  elastic,  the  pressure  of  the  steam  would  be  exerted 
at  right  angles  to  the  surfaces,  f g,  and  the  pressure  on  these  surfaces 
would  not  be  increased  or  diminished  if  the  elastic  substance  should 
spread  laterally.  If  it  should  do  so  and  thus  produce  pressures  in  the  di- 
rection g or  h , it  would  not  produce  any  strain  on  the  bolts,  a and  b,  to 
tear  them  apart,  but  such  pressures  would  have  a tendency  to  rupture  the 
boiler  on  the  line,/  k. 

The  effect  of  internal  pressure  in  a boiler  may  be  made  clear  in  still 
another  way.  Let  it  be  supposed  that  we  have  a cast-iron  boiler  the  in- 
side surface  of  which  is  formed  as  shown  in  fig.  146 — that  is,  it  is  serrated 
or  formed  like  steps,  with  vertical  and  horizontal  surfaces  as  shown.  It 
may  be  assumed,  without  leading  us  into  error,  that  the  pressure  of  the 
steam  is  exerted  at  right  angles  to  these  surfaces — that  is,  that  it  acts 
in  the  direction  indicated  by  the  darts.  Obviously  the  pressure  which 
tends  to  pull  apart  the  bolts,  a and  b,  is  only  that  represented  by  the 
vertical  darts,  and  which  acts  on  the  horizontal  surfaces,  and  the  total 
strain  which  these  bolts  must  resist  is  equal  to  the  area  of  these  sur- 
faces multiplied  by  the  pressure  per  square  inch.  But  if  we  draw  vertical 


Locomotive  Boilers. 


187 


lines,  c c',  d d' , e e' , etc.,  from  the  stepped  surfaces  to  the  diameter,  a b,  it 
will  be  apparent  that  the  area  of  the  horizontal  stepped  surfaces,  1 c,  2 d, 
3 e,  4 y,  f g,  etc.,  are  equal  to  o c',  c' d' , d'  e' , e'  f ,f  g' ',  etc.,  and  that  they 
are  equal  in  length  to  the  diameter,  a b , so  that  if  we  multiply  this  diame- 
ter by  the  length  of  the  boiler  and  the  pressure  per  square  inch,  it  will  give 
the  pressure  which  is  exerted  on  the  horizontal  surfaces,  1 c,  2 d,  3 e,  etc. 
It  may  now  be  imagined  that  the  steps  are  infinitely  small.  In  that  case 
the  internal  stepped  or  notched  surface  would  coincide  and  be  equivalent 
to  that  of  a cylinder  without  such  notches.  Therefore,  the  reasoning  which 
applies  to  the  one  will  apply  to  the  other.  The  effect  of  the  pressure  which 
acts  horizontally  or  in  any  other  direction  can  be  shown  in  the  same  way. 

The  sides  of  a boiler  must  therefore  be  made  strong  enough  to  resist 
the  pressure  which  the  steam  exerts  on  a surface  the  length  of  which  is 
equal  to  that  of  the  boiler,  and  the  width  equal  to  its  diameter. 

Question  242.  What  are  the  metals  principally  used  in  boiler  con- 
struction ? 

Answer . Formerly  wrought-iron  was  the  principal  metal  used  in  the 
construction  of  boilers,  but  it  has  now,  to  a very  great  extent,  been  super- 
seded by  soft  steel. 

QUESTION  243.  What  advantages  has  soft  steel  as  a material  for 
boilers  ? 

Answer.  Its  strength  to  resist  strains  of  tension  and  compression  is 
considerably  greater  than  that  of  iron,  thus  permitting  the  use  of  thinner 
plates.  Its  ductility  is  greater,  its  structure  more  homogeneous,  and  its 
quality  more  uniform. 

Question  244.  How  much  strain  per  square  inch  is  good  boiler-plate 
capable  of  resisting , and  how  much  is  it  safe  to  subject  it  to  ? 

Answer.  There  is  great  difference  in  the  tensile  strength*  of  rolled  iron 
boiler-plate,  but  that  of  good  plate  will  average  about  50,000  lbs.  per 
square  inch,  if  the  strain  is  applied  in  the  direction  of  the  “grain”  or  the 
fibres  of  the  iron,f  and  about  10  per  cent,  less  if  the  strain  is  applied  cross- 
wise of  the  grain.  It  has,  however,  been  found  by  experiment  that  when 
a tensile  strain  is  applied  to  a bar  of  iron  or  other  material,  it  is  stretched 
a certain  amount  in  proportion  to  the  length  of  the  bar,  and  to  the  degree 
of  strain  to  which  it  is  subjected.  If  this  strain  does  not  exceed  about 

* A force  exerted  to  pull  any  material  apart  is  called  a tensile  strain , and  if  exerted  to  com- 
press it  is  called  a compressive  strain. 

+ It  should  be  explained  that  in  the  process  of  manufacturing  iron  by  rolling,  the  iron  is 
stretched  out  into  fibres  in  the  direction  in  which  it  passes  between  the  rolls. 


188 


Catechism  of  the  Locomotive. 


one-fifth  of  that  which  would  break  the  bar,  it  will  recover  its  original 
length,  or  will  contract  after  being  stretched,  when  the  strain  is  removed, 
The  greatest  strain  which  any  material  will  bear  without  being  perman- 
ently stretched  is  called  its  limit  of  elasticity,  and  so  long  as  this  is  not 
exceeded,  no  appreciable  permanent  elongation  or  “ set  ” will  be  given  to 
iron  by  any  number  of  applications  of  such  strains  or  loads.  If,  however, 
the  limit  of  elasticity  is  exceeded,  the  metal  will  be  permanently  elongated, 
and  this  elongation  will  be  increased  by  repeated  applications  of  the  strain 
until  finally  the  bar  will  break.  At  the  same  time  the  character  of  the 
metal  will  be  altered  by  the  repeated  application  of  strains  greater  than  its 
elastic  limit,  and  it  will  become  brittle  and  less  able  to  resist  a sudden 
strain,  and  will  ultimately  break  short  ofT.  It  is  therefore  unsafe  to  sub- 
ject iron,  or,  in  fact,  any  other  material,  to  strains  greater  than  its  elastic 
limit.  This  limit  for  iron  or  steel  boiler-plates  may  be  taken  at  about 
one-fifth  its  breaking,  or,  as  it  is  called,  ultimate  strength.  It  should  be 
remembered,  however,  in  this  connection,  that  it  often  happens  that  the 
steam  pressure  is  not  the  greatest  force  the  boiler  must  withstand,  as 
sudden  or  unequal  expansion  and  contraction  are  probably  more  destruc- 
tive, to  locomotive  boilers  especially,  than  the  pressure  of  the  steam. 

Question  245.  What  is  the  relative  strength  of  wr ought-iron  and  mild 
steel  plates  ? 

Answer.  Good  wrought-iron  boiler-plates,  as  already  stated,  have  a 
tensile  strength  of  about  50,000  lbs.  per  square  inch,  and  mild  steel  about 
60,000  lbs. 

QUESTION  246.  What  are  the  most  important  qualities  which  boiler- 
plates should  possess  ? 

Answer.  The  first  quality  to  be  sought  for  in  a boiler-plate  is  strength. 
This  does  not  necessarily  imply  the  mere  power  to  resist  being  torn 
asunder  by  a dead  weight,  as  in  a testing  machine,  but  the  quality  to 
withstand,  without  injury,  the  many  and  varying  shocks  and  strains  it  is 
exposed  to  in  the  boiler-shop  and  in  actual  work.  Many  inferior  plates 
exhibit  as  great  a cohesive  strength  as  those  of  better  quality,  their  in- 
feriority consisting  in  their  brittleness  or  shortness,  want  of  “body”  or 
soundness,  imperfect  manufacture,  and  uncertain  character  or  quality. 
Toughness  and  ductility,  combined  with  great  tenacity,  and  also  closeness 
and  uniformity  of  texture  and  constancy  of  quality,  are  the  properties  and 
character  to  be  sought  for. 

QUESTION  247.  What  qualities  shoidd  boiler-plates  a?id  rivets  have  ? 

Answer.  All  iron  or  steel  plates  of  the  best  quality  should  have  a longi- 


Locomotive  Boilers. 


189 


tudinal  tenacity  of  not  less  than  50,000  lbs.  per  square  inch  of  section,  and 
an  ultimate  elongation  before  breaking  of  about  12  per  cent.,  and  if  not 
exceeding  1 inch  in  thickness,  should  bend  double  along  or  across  the 
fibre  when  red  hot,  and  if  T76  inch  thick  and  under,  they  should  bend 
double  when  cold  without  fracture. 

Good  iron  plates  should  bend  cold,  without  fracture,  to  the  following 
angles : 


i 

T6 

8 

8 

tV 

t 

f 

l 


Thickness  of  Plate. 


Along  the  Fibre. 


Across  the  Fibre. 


inch 


90  degrees 


55  degrees. 


80 

70 

55 

40 

30 

20 

15 


45 

35 

25 

20 

15 

10 


The  radius  of  the  corner  over  which  the  plates  are  bent  should  not  ex- 
ceed half  an  inch. 

Steel  boiler-plates  should  have  a tensile  strength  of  about  60,000  lbs. 
per  square  inch,  and  it  should  not  be  less  than  50,000,  nor  more  than 
70,000  lbs.,  and  when  broken  under  tension  the  ultimate  elongation  of  a 
test  piece  8 inches  in  length,  after  fracture,  should  be  not  less  than  20  per 
cent,  of  the  original  length.  Strips  not  less  than  2 inches  broad  and  10 
inches  long,  cut  from  plates  not  exposed  to  the  fire  in  service,  should  bear 
bending  cold  without  fracture  until  the  sides  are  parallel  at  a distance 
from  each  other  of  not  less  than  three  times  the  thickness  of  the  plate. 
Strips  taken  from  plates  which,  in  service,  will  be  exposed  to  the  fire, 
should  be  heated,  before  bending,  to  a cherry  red,  then  plunged  into 
water  of  about  80  degrees  temperature,  and  kept  there  until  of  the  same 
temperature  as  the  water.  They  should  then  stand  the  same  test  required 
for  the  pieces  which  are  bent  cold. 

The  material  of  which  rivets  are  made  should  have  a high  degree  of 
ductility.  A good  iron  rivet,  cold,  should  bend  double  without  fracture, 
and  its  head  should  flatten  out  by  hammering  when  hot  to  about  £ inch 


190 


Catechism  of  the  Locomotive. 


thick  without  fracture  or  fraying  at  the  edge.  A hot  rivet-shank,  when 
flattened  down  to  a thickness  equal  to  about  one-half  its  diameter,  should 
bear  a punch  driven  through  it  without  fracture  at  the  hole.* 

The  steel  of  which  rivets  are  made  should  always  be  of  the  mildest — 
that  is,  the  most  ductile — material,  because  if  it  is  not  of  this  character  they 
are  liable  to  become  hard  and  brittle  while  being  worked  and  in  use. 

The  resistance  of  steel  rivets  to  shearing  should  therefore  not  be  greater 
than  that  of  iron  rivets,  or  about  50,000  lbs.  per  square  inch  of  section. 

The  following  are  the  specifications  to  which  all  boiler  and  fire-box 
steel,  bought  by  the  Pennsylvania  Railroad,  must  conform  : 

Specifications  for  Boiler  and  Fire-Box  Steel  for  Pennsyl- 
vania Railroad  Company. 

1st.  A careful  examination  will  be  made  of  every  plate,  and  none  will 
be  accepted  that  show  mechanical  defects. 

2d.  A test  strip,  taken  lengthwise  of  each  plate,  without  annealing, 
should  have  a tensile  strength  of  55,000  lbs.  per  square  inch,  and  an 
elongation  of  30  per  cent,  in  section  originally  2 inches  long. 

3d.  Plates  will  not  be  accepted  if  the  test  shows  a tensile  strength  less 
than  50,000  lbs.,  or  greater  than  65,000  lbs.  per  square  inch,  nor  if  the 
elongation  falls  below  25  per  cent. 

4th.  Should  any  plates  develop  defects  in  working,  they  will  be  rejected. 

5th. . Manufacturers  must  send  one  test  piece,  which  must  be  as  near 
straight  as  possible,  24  inches  long  and  not  less  than  1^  inches  wide,  for 
each  plate. 

6th.  Both  test  piece  and  plate  must  be  stamped  with  the  shear  mark 
designated  by  this  company,  the  letter  designating  the  plate  and  with  a 
serial  number  according  to  the  number  of  plates  of  the  same  kind  on 
order,  all  to  be  placed  near  together.  In  addition  to  this,  and  in  order  to 
facilitate  matching,  a circle  of  white  lead  must  be  drawn  around  the  shear 
marks,  stamp  numbers  and  letters,  and  the  two  latter  repeated  in  white 
lead  on  both  test  piece  and  plate. 

7th.  The  sheared  edges,  at  shear  marks,  of  both  test  piece  and  plate, 
must  show  a fresh  shear  and  it  will  be  considered  sufficient  cause  for  re- 
jection of  the  plate  if  either  show  signs  of  having  been  annealed  after 
separation. 

8th.  No  plate  or  test  piece  will  be  accepted  unless  it  shows  the  before- 
mentioned  marks. 

* Wilson’s  “ Treatise  on  Steam  Boilers,” 


Locomotive  Boilers. 


191 


Question  248.  Why  should  the  greatest  strength  steel-plates  and  rivets 
not  exceed  a certain  limit  ? 

Answer.  Because  steel  of  a very  high  tensile  strength  is  usually  brittle 
and  liable  to  fracture,  whereas  soft  ductile  steel  usually  has  a compara- 
tively low  tensile  strength. 

Question  249.  How  are  boiler-plates  fastened  together  ? 

Answer.  By  rivets  which  are  made  with  a head  on  one  end,  and  are 
inserted  red  hot  in  holes,  drilled  or  punched  in  the  plates,  and  another 
head  is  then  formed  by  hammering,  or  by  steam,  or  hydraulic  pressure, 
on  the  other  end  of  the  rivet.  The  rivets  are  thus  made  to  fill  the  holes, 
and  in  cooling  contract  and  draw  the  plates  together. 

Question  250.  What  is  the  strength  of  riveted  seams  compared  with 
that  of  the  solid  plate  ? 

Answer.  The  strength  of  a riveted  seam  depends  very  much  upon  the 
arrangement  and  proportion  of  the  rivets  ; but  with  the  best  design  and 


Single  Riveted  Lap  Seam.  Scale  in.=l  in. 


construction,  the  seams  are  always  weaker  than  the  solid  plates,  as  it  is 
always  necessary  to  cut  away  a part  of  the  plate  for  the  rivet-holes,  which 
weakens  the  plate  in  two  ways  : 1.  By  lessening  the  amount  of  material 
to  resist  the  strains.  2.  By  weakening  that  left  between  the  holes.  The 
first  cause  of  weakness  is  obvious  from  an  inspection  of  an  ordinary  seam, 


192 


Catechism  of  the  Locomotive. 


riveted  with  a single  row  of  rivets,  figs.  147  and  148.  In  this  we  have  two 
plates  7-£  inches  wide  and  f thick  fastened  with  four  rivets  ^ inch  in  di- 
ameter and  If  inches  from  centre  to  centre.  The  section  of  the  plate 
calculated  with  decimals*  would  therefore  be  .375x7.5=2.81  square 
inches.  A piece  -ff  inch  wide  and  § inch  thick  would  be  removed  to  form 
each  hole,  or  a sectional  area  for  the  whole  plate  of  .375  x .6875  x 4=1.03 
square  inches,  so  that  the  section  of  the  plate  would  be  reduced  through 
the  holes  2.81  — 1.03=1.78  square  inches.  In  other  words,  on  the 
- dotted  line,  a b,  it  will  have  only  about  63  per  cent,  of  the  sectional  area 
of  the  solid  plate. 

The  second  cause  of  the  reduction  of  strength  is  owing  to  the  injury 
sustained  by  the  plates  during  the  process  of  punching.  The  knowledge 
existing  regarding  this  subject  is  not  very  satisfactory,  although  numerous 
experiments  have  been  made  to  determine  the  exact  amount  of  weakening 
caused  by  punching  plates.  It  is,  however,  certain  that  in  many  cases  the 
strength  of  the  metal  left  between  the  holes  of  boiler-plates  is  reduced 
from  10  to  25  per  cent,  by  the  process  of  punching.  It  is  probable,  how- 
ever, that  soft  ductile  metal  is  injured  less  than  that  which  is  harder  and 
more  brittle.  Some  kinds  of  steel  plates  are  especially  liable  to  injury 
from  punching.  It  is  also  probable  that  the  condition  of  the  punch,  and 
the  proportions  of  the  die  used  with  it,  have  much  to  do  with  its  effect 
upon  the  metal. 

QUESTION  251.  How  can  the  injury  done  to  boiler-plates  by  punching 
be  prevented? 

Answer.  It  has  been  shown  that  the  injury  to  plates  from  punching  is 
confined  to  a narrow  area  around  the  hole,  and  that  by  punching  the  hole 
smaller  than  required,  and  then  reaming  it  or  drilling  it  to  the  required 
size,  the  weakened  portion  of  the  plate  is  removed,  leaving  that  portion 
between  the  holes  equal,  or,  as  has  been  shown  in  some  experiments,!  of 
greater  strength  than  the  original  plate.  It  has  also  been  shown  by  some 
experiments  that  annealing  steel  plates  after  punching  restores  them  to 
their  original  strength;  but  with  the  mild  steel  now  made  there  is  little 
need  of  this  precaution,  and  there  is,  perhaps,  more  danger  of  damaging 
the  plates  by  careless  attempts  at  annealing  than  by  deterioration  of  metal 
in  punching. 


*In  the  following  calculations  all  the  dimensions  have  for  convenience  been  reduced  to 
decimals. 

+ See  a description  of  Tensile  Tests  of  Iron  and  Steel  Bars,  by  Peter  D.  Bennett,  in  the  Pro- 
ceedings of  the  Institution  of  Mechanical  Engineers,  for  February,  1886. 


Locomotive  Boilers. 


193 


Question  252.  How  may  a boiler  seam  like  that  shown  in  fig.  147 
and  148  break  ? 

Answer.  It  may  break  in  three  different  ways  : 

1.  By  a plate  tearing  between  the  rivet  holes  on  the  line  a b. 

2.  By  the  rivets  shearing  off. 

3.  By  the  plate  in  front  of  the  rivets  crushing,  as  shown  in  fig.  149,  or 
splitting  the  plate  at  right  angles  to  the  seam,  as  shown  in  fig.  150. 


Scale  ^ in.=l  in. 


Question  253.  How  can  the  strength  of  a boiler  seam  be  calculated  at 
each  of  these  three  points  ? 

Answer.  The  strength  through  the  rivet  holes  is  calculated  by  taking 
THE  AREA  IN  SQUARE  INCHES  OF  THE  METAL  WHICH  IS  LEFT  BETWEEN 
THE  RIVET  HOLES,  AND  MULTIPLYING  IT  BY  THE  ULTIMATE  STRENGTH 
OF  THE  METAL  AFTER  THE  HOLES  ARE  MADE.  Thus,  in  fig.  147,  the 
area  of  each  of  the  plates  between  the  rivet  holes  is  1.78  square  inches. 
As  already  stated,  good  iron  boiler-plate  will  break  at  a strain  of  about 
50,000  lbs.  in  the  direction  of  its  fibres.*  The  calculation  for  the  strength 
through  the  holes  would  therefore  be:  1.78 x 50,000=89,000  lbs.  If  the 
holes  aie  punched  and  not  afterward  reamed  or  drilled  the  strength  of  the 
plates,  as  already  explained,  would  be  considerably  reduced,  and  a lower 
tensile  strength  must  be  used  in  calculating  the  strength  of  the  seam. 

It  has  also  been  found  by  experiment  that  the  strength  of  rivets  to  resist 

* Boiler-plates  should  always  be  so  arranged  that  the  greatest  strain  will  come  on  them  in  the 
direction  of  their  greatest  strength,  which  is  parallel  with  the  fibres  of  the  metal. 


194 


Catechism  of  the  Locomotive. 


shearing  is  about  the  same  as  that  of  good  boiler-plate  to  resist  tearing 
apart,  or  50,000  lbs.  per  square  inch.  The  strength  of  the  rivets,  therefore, 
is  calculated  by  multiplying  the  area  in  square  inches  of  one 
rivet  by  the  number  of  rivets,  and  the  product  by  the  strength 
of  the  metal  to  resist  shearing.  The  calculation  for  figs.  147  and 
148  would  therefore  be  : 

Area  of  rivet=.3712  x 4 x 50,000=74,240, 

or  somewhat  less  than  the  strength  of  the  plates  through  the  holes. 

The  resistance  offered  by  a plate  to  the  crushing  strain  of  a rivet  has 
been  found  also  by  experiment  to  be  about  90,000  lbs.  per  square  inch.  It 
can  be  proved  that  the  area  which  resists  the  crushing  strain  of  a rivet  in 
a plate,  fig.  149,  is  measured  by  multiplying  the  diameter  of  the 
rivet  by  the  thickness  OF  the  plate.  The  calculation  for  the 
strength  of  this  part  of  the  seam  will  therefore  be  : diameter  of  hole= 
.6875  x .375  x 4 x 90,000=92,812. 

The  strength  of  the  solid  plate  without  any  holes  in  it  would  be  equal 
TO  ITS  SECTIONAL  AREA  MULTIPLIED  BY  50,000  LBS.,  or  7.5  X .37,5  X 50,- 
000  = 140,625  lbs.  The  ultimate  strength  of  the  seam  would  then  be  as 
follows : 

Rivets (shearing)  = 72,240  lbs. 

Plates  through  rivet  holes (tearing)  = 89,000  “ 

Plates  in  front  of  rivets (crushing)  = 92,812  “ 

Solid  plate (tearing)  =140,625  “ 

It  will  thus  be  seen  that  the  strength  of  the  weakest  part  of  the  above 
seam,  fastened  with  a single  row  of  rivets,  is  very  little  more  than  half 
(51.3  per  cent.)  of  that  of  the  solid  plates.  It  will  be  noticed  that  the 
plates  between  the  holes  have  an  excess  of  strength  over  the  rivets,  which 
is  desirable,  because  the  plates  are  liable  to  more  or  less  injury  from 
punching. 

Question  254.  What  are  the  usual  proportions  for  single-riveted  lap 
seams  ? 

Answer.  The  following  table  gives  the  usual  proportions  for  such 
seams : 


Locomotive  Boilers. 


195 


SINGLE-RIVETED  LAP  JOINTS. 


Iron  Plates,  Iron  Rivets. 

Steel  Plates,  Iron  Rivets. 

Thickness  of 

* Diameter 

Pitch  of 

Thickness  of 

* Diameter 

Pitch  of 

Plates. 

of  Rivets. 

Rivets. 

Plates. 

of  Rivets. 

Rivets. 

t5B  inch. 

Is inch. 

li§  inch. 

ts  inch. 

U inch. 

1t95  inch. 

3 “ 

1 “ 

1|  “ 

i “ 

| “ 

19  il 

1TS 

7 H 

16 

13  I* 

m “ 

ts  “ 

if  “ 

iff  “ 

i 

7 u 

5 

2 

1 

2 

1 “ 

iff  “ 

5 « 

5 

II  “ 

2j's  “ 

1 “ 

if  “ 

Hf  “ 

i “ 

i*  “ 

2j%  “ 

I “ 

Its  “ 

17 

is 

f “ 

if  “ 

2f  “ 

7 U 

If  “ 

2 

1 

U “ 

2i5b  “ 

1 

If  “ 

Question  255.  Is  the  maximum  strength  of  seams  the  chief  aim  in 
designing  a boiler  ? 

Answer.  No  ; a tight  joint  is  of  the  first  importance,  for  should  leakage 
occur  corrosion  may  soon  alter  any  carefully  calculated  proportions  of  the 
respective  sections  in  the  joint.  Indeed,  it  may  be  affirmed  that  in  the 
majority  of  cases  the  safety  of  a boiler  depends,  in  the  long  run,  more 
upon  the  tightness  than  the  actual  strength  of  the  joints,  since  a large 
factor  of  safety  is  usually  allowed.! 

Question  256.  How  may  a single-riveted  lap  seam  be  made  stronger 
than  that  illustrated  by  figs.  147  and  148  ? 

Answer.  The  most  obvious  way  of  doing  this  is  to  increase  the  pitch — 
that  is,  the  distance  from  centre  to  centre — and  the  diameters  of  the  rivets, 
which  would  leave  more  metal  between  the  holes,  and  thus  strengthen  the 
seam  at  its  weakest  part.  But  if  this  is  done,  it  is  said  that  there  is  diffi- 
culty in  keeping  the  seams  water-tight,  as  the  plates  are  then  liable  to 
spring  apart  between  the  rivets.  Another  way  of  increasing  the  strength 
of  the  seam  is  to  drill  the  rivet  holes.  As  already  stated,  the  difference  in 
the  strength  of  the  metal  left  between  drilled  and  punched  holes  has  been 
shown  to  be  from  10  to  25  per  cent.  There  is  also  another  advantage  in 
drilling  the  holes  for  rivets.  In  punching  them,  it  is  necessary  to  punch 
each  plate  separately,  and  even  with  the  utmost  care  and  skill  it  is  im- 

* This  is  the  diameter  of  the  rivets  before  being  driven  ; the  holes  are  usually  made  4s  inch 
larger. 

t Wilson’s  “Treatise  on  Steam  Boilers.” 


196 


Catechism  of  the  Locomotive. 


possible  to  get  the  holes  to  match  perfectly.  Some  of  them  will  overlap 
each  other,  as  shown  in  fig.  151,  so  that  when  the  rivet  is  set,  it  will  assume 
somewhat  the  form  shown  in  fig.  152.  There  is  then  danger  that  those 
rivets  which  fill  the  holes  that  match  each  other  will  be  subjected 
to  an  undue  strain.  If,  for  example,  we  have  five  rivet  holes,  as 
shown  in  fig.  153,  and  only  the  centre  ones  correspond  with  each  other, 
then  the  rivets  in  all  the  other  holes  will  assume  somewhat  the  form 
shown  in  fig.  152,  and  therefore  the  centre  rivet,  c,  in  fig.  153,  which  fits 


Fig.  151. 


Fig.  153. 

Unmatched  Rivet  Holes.  Scale  *4  in.=l  in. 


the  holes  accurately,  must  take  the  strain  of  the  other  four  until  they  draw 
up  “to  a bearing.”  Under  such  circumstances,  which  are  not  unusual, 
there  will  be  great  danger  either  of  shearing  off  the  rivet,  c,  or  of  starting 
a fracture  in  the  plates,  as  indicated  by  the  irregular  line,  a b,  between  the 
adjoining  rivets.  It  is  also  obvious  that  a rivet  like  the  one  in  fig.  152 
will  not  hold  the  plates  together  so  well  as  one  which  fits  better,  as  shown 
in  section  in  fig.  148,  and  therefore  there  is  more  danger  of  leakage  be- 
tween the  plates  from  badly  fitted  rivets  than  from  those  which  fill  the 
holes  more  perfectly ; consequently  rivets  which  fit  badly  must  be  placed 


Locomotive  Boilers. 


197 


nearer  together  than  those  which  are  well  fitted.  It  is  true  that  rivets 
which  are  set  with  a riveting  machine  fill  any  inaccuracies  of  the  holes 
better  than  those  which  are  set  by  hand.  But  even  if  they  are  made  to 
fill  the  holes,  as  shown  in  fig.  154,  they  are  still  not  so  strong  to  resist 
shearing  nor  so  efficient  in  holding  the  plates  together  as  they  would  be  if 


Fig-.  154. 


the  holes  conformed  more  perfectly  to  each  other.  In  drilling  the  holes, 
the  second  plate  can  be  drilled  from  the  holes  in  the  first,  so  that  the 
holes  in  each  one  will  correspond  with  the  other  perfectly.  The  rivets 
will  therefore  fit  more  accurately,  and  consequently  can  be  spaced  further 
apart,  and  still  keep  the  plates  tight,  and  thus  there  will  be  more  mate- 
rial between  the  holes,  which  is  the  weakest  part  of  the  seam.  It  has  been 
shown  that  a rivet  ^ inches  in  diameter  has  a resistance  to  shearing  of 
18,560  lbs.  There  is  therefore  no  advantage  with  plates  f inch  thick  in 
spacing  such  rivets  further  apart  than  1||  from  centre  to  centre,  because 
the  metal  of  50,000  lbs.  of  tensile  strength  which  is  left  between  drilled 
holes  that  distance  apart  would  be  slightly  stronger  than  the  rivets.  If, 
therefore,  the  rivets  are  placed  further  apart,  their  diameter  must  be  in- 
creased. There  is,  however,  a limit  beyond  which  the  diameters  of  rivets 
cannot  be  increased  with  advantage,  because  if  we  increase  their  diame- 
ters, their  sectional  area  to  resist  shearing  is  increased  in  proportion  to  the 
square  of  the  diameter , whereas  the  section  of  metal  in  the  plate  to  resist 
crushing  is  increased  only  in  proportion  to  the  diameter.  This  will  be 
apparent  if  we  compare  a rivet  \ inch  with  one  1 inch  in  diameter.  The 
first  has  a sectional  area  of  .1963  inches,  the  other  .7854  inches,  or  four 
times  that  of  the  first  one.  Now  the  area  which  resists  the  crushing  strain 
of  the  rivets  is  increased  only  in  proportion  to  their  diameters,  or  is  twice 
as  much  for  the  one  as  for  the  other.  If,  therefore,  we  increase  the  diame- 
ters, of  the  rivets,  we  very  soon  reach  a point  at  which  the  plate  has  less 
strength  to  resist  crushing  than  the  rivet  has  to  resist  shearing.  The 
diameter  of  rivet  which  will  give  just  the  same  resistance  to  both  strains 
varies  with  the  thickness  of  the  plates ; with  f inch  plates  a £ inch  rivet 
will  have  a resistance  to  shearing  of  30,065  lbs.  and  the  plate  in  front  of  it 
a resistance  to  crushing  of  29,530  lbs.  A £ inch  rivet  is,  therefore,  the 


198 


Catechism  of  the  Locomotive. 


largest  size  which  can  be  used  to  advantage  in  f inch  plates.  If  now  we 
were  to  space  such  rivets  so  far  apart  that  the  metal  left  between  the 
holes  would  have  a strength  just  equal  to  that  of  the  rivets,  we  would  have 
the  strongest  possible  seam  that  can  be  made  with  a single  row  of  rivets. 
This  distance  would  be  If  inches  between  the  edges  of  the  rivets,  or  2f 


Fig.  155.  Single-Riveted  Lap  Seam.  Scale  J4  in.=l  in. 


inches  from  centre  to  centre,  as  shown  in  fig.  155.  The  following  table 
will  show  the  strength  of  such  a seam  composed  of  four  rivets,  and  two 
plates  10^-  inches  wide,*  with  drilled  holes  : 

Plates  through  rivet  holes .(tearing)  118,125  lbs. 

Rivets (shearing)  120,260  “ 

Plates  in  front  of  rivets (crushing)  118,125  “ 

Solid  plates (tearing)  196,875  “ 

From  this  it  is  seen  that  the  strength  of  the  seam  with  drilled  plates  is 
60  per  cent,  of  that  of  the  solid  plates,  or  it  is  about  18^  per  cent,  stronger 
than  that  made  with  plates  having  punched  holes  and  the  rivets  nearer 
together.  It  should  be  noted  that  a great  part  of  the  superiority  of  the 
seams  made  with  drilled  holes  is  due  to  the  superior  accuracy  of  the 
work  done  in  that  way,  which  makes  it  possible  to  use  larger  rivets  spaced 
further  apart.  It  is  probable  that  with  the  use  of  some  recently  designed 
machines,  intended  to  produce  greater  accuracy  in  punching  rivet  holes, 

* It  has  been  necessary  to  take  for  an  illustration  plates  of  a different  width  from  the  preced- 
ing example,  in  order  to  get  an  even  number  of  spaces  between  the  rivets  in  each  case. 


Locomotive  Boilers. 


199 


part  of  the  above  advantage  maybe  realized  with  that  kind  of  work.  The 
greatest  distance  that  rivets  may  be  spaced  apart  without  incurring  dan- 
ger of  leakage  between  the  plates  must,  however,  be  determined  more  by 
practical  than  theoretical  considerations.  It  is  certain,  however,  that 
if  their  heads  are  made  sufficiently  large,  rivets  may  be  spaced  much  fur- 
ther apart  than  they  are  in  ordinary  practice,  and  the  seams  still  be  kept 
tight,  if  the  work  is  done  with  the  requisite  accuracy  and  care. 

QUESTION  257.  What  must  be  the  proportions  for  a single-riveted  lap 
seam  made  of  iron  plates  and  with  iron  rivets  to  get  the  maximum 
strength  ? 

Answer.  If  the  plates  have  a tensile  strength  and  the  rivets  a resistance 
to  the  shearing  equal  to  50,000  lbs.  per  square  inch,  THE  rivet  holes 
(not  the  diameter  of  the  rivets  cold)  should  be  2f  times  the  thick- 
ness of  the  plates,  and  the  pitch  of  the  rivets  from  centre  to 

CENTRE  SHOULD  BE  7 TIMES  AND  THE  OVERLAP  OF  THE  PLATES  0 TIMES 
their  THICKNESS.  Fig.  155  represents  a seam  of  these  proportions.  In 
the  table  on  the  next  page  the  strength  of  a seam  like  that  represented  by 
figs.  147  and  148  is  given  in  the  vertical  column,  A,  and  that  of  the  one 
shown  by  fig.  155  is  given  in  column  B.  The  strength  per  lineal  inch  of 
the  seams  is  given  in  the  eighth  horizontal  line.  That  of  the  first  one  is 
9,898  lbs.,  whereas  that  of  the  second  one  is  11,250  lbs.  per  lineal  inch. 

QUESTION  258.  What  difference  shoidd  there  be  in  the  proportions  of 
single-riveted  lap  seams  if  made  of  steel  instead  of  iron  plates,  and  with 
steel  rivets  ? 

Answer.  As  steel  rivets  with  sufficient  ductility  have  no  greater  strength 
to  resist  shearing  than  iron  rivets,  the  one  kind  should  be  of  the  same  size 
as  the  other ; but  as  steel  plates  have  about  20  per  cent,  more  tensile 
strength  than  iron  ones,  the  amount  of  metal  between  the  rivet  holes  may 
be  less  if  the  plates  are  made  of  steel  than  if  they  are  of  iron.  Thus  in 
the  seam  represented  by  fig.  155  the  rivet  hole  is  f inch  in  diameter,  and 
the  width  of  the  metal  between  the  holes  is  If  inches.  Their  sectional 
area  and  strength  is  as  follows  : 

Rivet  area,  .6013  x 50,000=  30,065  lbs. 

Plate  area,  If  x f =.65625  x 50,000=32,812  lbs. 

If  the  plate  is  of  steel  and  the  space  between  the  rivets  is  made  If  or  20 
per  cent,  less  than  shown  in  fig  155,  then  its  strength  would  be  as  follows : 


If  x f =.5156  x 60,000=30,937  lbs., 


STRENGTH  OF  DIFFERENT  KINDS  OF  RIVETED  SEAMS. 


200 


Catechism  of  the  Locomotive. 


- 

1 

•iPiW  ilVM.  ‘niBas 
deq  p3j3Ai^-3iSuis 

■i  i . 

flj 

4-*  \$0  \flO 
(/)  iv\  io\ 

w 

lbs. 

262,500 

163,120 

236,250 

18,124 

22,500 

per  ct. 

80.55 

’Il3A\.  miAV 
‘SSI  ‘UIB3g 

duq  p3j3Ai^-9[Su;s 

1 S i 

lbs. 

262,500 

153,070 

236,250 

14,578 

18,750 

per  ct. 

77.75 

0 

'JI3AV  tom 
lifl  ‘SlJ  ‘UH33S 
dBq  p313AI^I-3|SuiS 

c .S  - 
2 35  g 

lbs. 

148,480 

114,840 

185,624 

15,312 

18,750 

per  ct. 

81.66 

fa 

•^SI  •Slki  ‘UIB3g 
dnq  p353Ai^j-9^qnoQ 

Steel. 

% in. 

3%  “ 

2ft  “ 

lbs. 

180,390 

177,185 

177.183 

16,874 

22,500 

per  ct. 

75. 

w 

•UJB3S 

duq  p3j3Ai^-3|qnoQ 

Iron. 

% in. 

3%  “ 

2%  “ 

lbs, 

180,390 

182,810 

177,183 

14,318 

18,750 

per  ct. 

76.36 

Q 

\4QI  'Sitf  ‘UIB3S 
dBq  p3i3Ai^-3iqnoQ 

Iron. 

Min. 

3 “ 

2M  “ 

lbs. 

132,010 

126,562 

151,875 

14,062 

18,750 

per  ct. 

74.46 

u 

•XUB3S 

d^T  psisAi-jj-siSuis 

T3  .S  i 

QJ 

« * 3f 

lbs. 

131,250 

123,748 

118,125 

13,125 

22,500 

per  ct. 

58.33 

m 

■QQI  •Sitf  ‘U1B3S 
dBq  p313AI-JJ-3[Su;S 

c .S  - 

& s £ 

lbs. 

131,250 

120,260 

118,125 

11,250 

18,750 

per  ct. 

60. 

1 

< 

•8H  pn* 

Lfl  ‘SSlJ  lUIB3g 
du'J  p313AI-y-3lSmg 

'a  .g  : 

2 35  g 

lbs. 

74,240 

89.060 

92,812 

9,898 

18,750 

per  ct. 

52.78 

Material  of  plates 

Diameter  of  rivet  holes 

Straight  pitch  of  rivets 

Strength  of  rivets  to  resist  shearing 

Strength  of  plates  through  rivet  holes  to  resist  tearing 

Strength  of  plates  in  front  of  rivets  to  resist  crushing 

Minimum  strength  of  seam  per  lineal  inch 

Strength  of  plate  per  lineal  inch 

Strength  of  seam  in  percentage  of  solid  plate 

l 

*i  ©*  eo  ■<*<  oot^oooj  o 

Locomotive  Boilers. 


201 


or  a little  in  excess  of  the  strength  of  the  rivets.  Therefore,  if  steel 

PLATES  ARE  USED  THE  PITCH  OF  THE  RIVETS  MAY  BE  6 TIMES  THE  THICK- 
NESS OF  THE  PLATES  FOR  A SINGLE-RIVETED  LAP  SEAM  OF  MAXIMUM 
STRENGTH. 

The  strength  of  a seam  proportioned  in  this  way  is  given  in  column  C 
of  the  table,  and  is  22,500  lbs.  per  lineal  inch.  A comparison  of  the 
strength  per  lineal  inch  shows  the  advantage  which  is  gained  in  strength 
by  using  larger  rivets  spaced  further  apart  than  those  ordinarily  used,  and 
also  the  greater  strength  of  seams  made  of  steel  plates. 

Question  259.  What  other  methods  are  there  of  making  boiler  seams 
which  are  stronger  than  those  which  have  been  described? 

Answer.  In  order  to  increase  the  strength  of  seams  they  are  often  made 
with  two  rows  of  rivets,  and  what  is  called  a “welt,”  or  covering-strip,  is 
sometimes  used,  the  latter  with  both  single  and  double-riveted  seams. 
What  are  called  “butt-joints,”  or  seams,  have  been  used  a great  deal  in 
Europe,  and  of  late  years  have  been  adopted  to  a limited  extent  in  this 
country. 

Question  260.  How  are  the  rivets  arranged  when  two  rows  are  used? 

Answer.  They  are  sometimes  placed  just  behind  each  other,  as  shown 
in  fig.  156,  which  is  called  chain-riveting. 


Fig.  156.  Chain-Riveted  Seams.  Scale  *4  in.=l  in. 

A much  better  arrangement  is  to  place  them  alternately  in  the  two 
rows,  as  shown  in  fig.  157.  Rivets  arranged  in  that  way  are  said  to  be 
“ staggered ,”  or  placed  zig-zag. 


202 


Catechism  of  the  Locomotive. 


In  a single-riveted  seam  each  rivet  must  resist  a strain  equal  to  that  on 
the  metal  between  two  adjoining  rivets.  In  a double-riveted  seam  one- 
half  the  strain  on  the  metal  between  two  contiguous  rivets,  in  one  row,  is 
resisted  by  a rivet  in  the  other  row.  Thus  in  fig.  157  the  rivet, g,  will  take 
one-half  the  strain  on  the  metal  between  the  rivets  c and  f.  Consequently, 
the  area  of  the  metal  between  c and  f and  their  distance  apart,  may  be 
very  much  greater  than  it  would  be  in  a single-riveted  seam. 

Question  261.  What  are  the  usual  proportions  for  double-riveted 
seams  ? 

Answer.  The  following  table,  copied  from  “ The  Elements  of  Machine 
Design,”  by  W.  C.  Unwin,  gives  proportions  for  such  seams  which  are  very 
commonly  used : 


PROPORTIONS  FOR  DOUBLE-RIVETED  SEAMS. 


Ikon 

Plates,  Iron  Rivets. 

Steel  Plates,  Iron  ’ 

Rivets. 

Thickness  of 

Diameter  of 

Pitch  of 

Thickness  of 

Diameter  of 

Pitch  of 

Plates. 

Rivets. 

Rivets. 

Plates. 

Rivets. 

Rivets. 

% inch. 

% inch. 

3 inch. 

% inch. 

%.  inch. 

3A  inch. 

t7s  “ * 

13  “ 

16 

8 A “ 

TS 

13  *4 

TS 

2J4  “ 

H “ 

Vs  “ 

8 H “ 

H “ 

Vs  “ 

2x9s  “ 

A “ 

Vs  “ 

3/4  “ 

9 kk 

xe 

% “ 

2A  11 

Vs  “ 

11  “ 

3i3s  “ 

% “ 

11  “ 

2%  “ 

H “■ 

Its 

3A  “ 

H “ 

1*  “ 

2%  “ 

Vs  “ 

m “ 

3 Vs  “ 

Vs  “ 

Ws  “ 

211  “ 

l 

m “ 

3J4  “ 

1 

1 14  “ 

211  “ 

QUESTION  262.  What  should  be  the  diagonal  pitch  of  the  rivets  in  a 
double-riveted  seam — that  is,  the  distance  between  the  centres  of  the  rivets,  c 
andg,  or  g andf,  of  fig.  137? 

Answer.  It  has  been  found  by  experiment*  that  the  net  metal  measured 
on  zigzag  line,  c g f,  fig.  157,  should  be  about  one-third  in  excess  of  that 
measured  straight  across.  If  there  is  not  that  much  excess  the  plates  will 
be  weaker  straight  across,  and  will  break  on  the  line,  a b.  If  the  diago- 
nal pitch  (or  the  distance  from  centre  to  centre  of  rivets,  c and  g,  or  g 

* See  “ Report  upon  Experiments  and  Abstract  of  Results  of  Experiments  on  Riveted  Joints,” 
in  Proceedings  of  the  Institution  of  Mechanical  Engineers  for  April,  1885. 


Locomotive  Boilers. 


203 


and  /)  IS  MADE  THREE-QUARTERS  OF  THE  PITCH  OR  DISTANCE  BETWEEN 
THE  CENTRES  OF  RIVETS  ( C and  /)  ON  THE  SAME  LINE,  it  will  give  a good 
proportion  for  such  a seam. 


a 


Fig.  157.  Double-Riveted  Lap  Seams.  Scale  34  in.=l  in.  Fig.  158. 


QUESTION  268.  How  should  a double-riveted  seam  be  proportioned  to 
have  the  maximum  a7nount  of  strength  ? 

Answer.  To  proportion  such  a seam  the  rivet  hole,  for  the  reasons 
explained,  should  be  made  of  the  same  diameter  as  for  a single-riveted 
seam — that  is,  2£  times  the  thickness  of  the  plates.  For  plates  f inch 
thick  the  rivet  holes  would  therefore  be  inch  diameter.  It  has  been 
explained,  and  is  shown  in  fig.  157,  that  the  seam  with  two  rows  of  rivets 
the  rivet  strength — that  is,  their  resistance  to  shearing,  is  twice  that  of  a 
seam  with  one  row,  because  the  number  of  rivets  is  doubled.  Con- 
sequently the  amount  of  metal  between  the  rivets  may  be  twice  as  great 
as  in  a single-riveted  seam.  It  has  been  found  by  experiment  and  calcu- 
lation that  if  the  diameter  of  rivets  for  a double-riveted  seam  is  made 
2^  times  the  thickness  of  the  plates,  and  the  pitch — with  iron  plates — is 
made  11  times,  and  for  steel  plates  9^  times  their  thickness,  that  it  will 
give  a seam  of  nearly  equal  strength  to  resist  the  shearing  of  the  rivets 
and  the  tearing  and  crushing  of  the  plates. 

The  strength  of. such  seams  has  been  calculated,  and  the  results  are 
given  in  columns  E and  F of  the  table  on  page  200.  Column  D gives  the 
strength  of  a seam,  represented  by  fig.  157  and  proportioned  as  specified 


204 


Catechism  of  the  Locomotive. 


in  the  above  table  of  proportions  for  double-riveted  seams.  The  strength 
per  lineal  inch  is  given  in  the  eighth  horizontal  line  of  the  large  table,  on 
page  200,  and  shows  the  superiority  of  double-riveting,  and  also  the  gain 
from  the  use  of  large  rivets  and  greater  pitch  and  of  steel  plates. 

The  distance  that  the  rivets  for  a double-riveted  seam  should  be  spaced 
on  a zigzag  line  is  three-quarters  of  the  pitch  on  a straight  line,  or  8£ 
times  the  thickness  of  iron  and  7 times  that  of  steel  plates. 

Question  264.  What  is  the  form  of  construction  of  boiler  seams  made 
with  a lap  and  a welt  or  covering-strip  ? 

Answer.  The  plates  {a  b,  figs.  159  and  160)  are  lapped  over  each  other 
as  for  an  ordinary  seam.  Another  plate,  c,  is  then  placed  on  the  inside  of 
the  seam  and  bent  so  as  to  conform  to  the  lap  of  the  two  plates.  The 
rivets,  r r,  fig.  160,  whether  a double  or  single  row,  pass  through  all  three 
plates,  and  two  more  rows  of  rivets,  d d,  are  put  next  to  the  edges  of  the 


a 


Single-Riveted  Seam  with  Welt.  Scale  in.=l  in. 


covering  plate  or  welt,  c.  It  is  plain  that  the  strength  of  the  seam,  r r,  is 
increased  up  to  a certain  point  by  an  amount  just  equal  to  that  of  the 
rivets,  d d,  in  the  edges  of  the  covering  plate.  If,  however,  these  are 


Locomotive  Boilers. 


205 


placed  too  close  together,  the  plates,  a and  b , will  be  weaker  through  the 
outside  rows  of  rivets,  d dy  than  the  seam  is  through  either  of  the  outside 
ones  and  the  middle  one  taken  together.  If,  for  example,  we  take  a sin- 
gle-riveted seam,  like  that  shown  in  fig.  118,  whose  strength  is  only  a 
little  more  than  half  that  of  the  solid  plate,  and  should  add  to  it  a cover- 
ing plate,  as  shown  in  fig.  159,  and  then  space  the  rivets  in  the  edges  of 
the  covering  plate  the  same  distance  apart  as  in  the  middle  seam,  then 
obviously  the  plates  would  be  just  as  liable  to  break  through  the  outer 
rows  of  holes  as  through  the  centre  row  before  the  covering  plate  was 
added.  If,  however,  the  holes  in  the  two  outside  plates  are  spaced  at  say 
twice  the  distance  apart,  or  3f  inches,  then  the  only  way  the  seam  can 
break  through  the  outer  rows  of  holes  is  by  shearing  the  rivets,  because 
the  plates  between  the  holes  are  then  stronger  than  the  rivets.  But 
before  these  rivets  can  be  sheared,  the  centre  seam  must  give  way.  Thus 
the  strength  of  such  a seam  is  equal  to  the  sum  of  the  strength  at 
THE  WEAKEST  POINTS  OF  THE  MIDDLE  AND  THE  OUTSIDE  SEAMS.  The 
strength  of  the  plates  between  the  holes  of  the  outside  rows  of  rivets 
must,  however,  be  as  great  as  the  sum  referred  to,  otherwise  the  seam  will 
be  the  weakest  at  that  point,  and  the  failure  will  occur  there.  The  rivets 
in  the  outside  rows  should  be  spaced  at  least  twice  as  far  apart  as  those 
in  the  middle  seam.  The  number  of  rivets  to  resist  shearing  will  then  be 
50  per  cent,  greater  than  in  a single-riveted  seam.  Welted  seams  of  this 
kind  are  sometimes  made  with  a double  row  of  rivets  between  the  two 
outer  rows. 

QUESTION  265.  What  advantage  has  such  a seam  over  seams  without 
a welt? 

Answer.  The  strength  of  a seam  is  increased  by  an  amount  equal  to 
that  of  the  welt.  Thus,  column  G,  in  the  table  on  page  200,  gives  the 
strength  of  a seam  like  that  in  column  A,  but  with  a welt  added ; column 
//gives  the  strength  of  seam  B with  a welt  added  and  column  / gives  the 
strength  of  seam  C,  welted.  A comparison  of  the  strength  of  the  different 
seams  per  lineal  inch  in  the  eighth  horizontal  line  shows  the  great  increase 
in  strength  which  results  from  the  addition  of  a welt. 

Question  266.  How  are  butt-joints  or  seams  made? 

Answer.  In  these  the  ends  of  the  two  plates  abut  against  each  other, 
as  shown  at  a,  in  figs.  162,  with  a covering  strip  or  welt,  b,  which  is 
shaded  black  in  the  engravings,  on  one  or  both  sides.  In  some  cases  a 
single  welt  or  covering  strip,  b , figs.  161  and  162,  is  used  with  either  two 
or  four  rows  of  rivets.  Such  a seam  has  no  more  strength  than  a lap 


206 


Catechism  of  the  Locomotive. 


Fig.  161. 

Single-Riveted  and  Single-Welt  Butt  Seam. 


Fig.  162. 
Scale  34  in.=l  in. 


Fig.  163. 

Double-Riveted  and  Double-Welt  Seam. 


Fig.  164. 
Scale  34  in.=l  in. 


Locomotive  Boilers. 


207 


seam  like  those  shown  by  figs.  148  or  157.  In  fact,  it  consists  of  two  lap 
seams.  The  circumferential  seams  of  boilers  are,  however,  often  made  in 
this  way  in  Europe,  so  as  to  get  all  the  plates  in  the  cylindrical  part  of  the 
boiler  flush  with  each  other.  Another  method  of  making  a butt  seam  is 
shown  by  figs.  165  and  166.  In  this  the  outside  covering  strip,  b,  is  made 
narrower  than  the  inside  one,  a,  and  the  two  middle  rows  of  rivets,  r r, 
are  spaced  as  in  a single-riveted  seam.  The  outside  rivets,  d d,  are  then 


Fig.  165. 

Double-Riveted  and  Double-Welt  Seam. 


Fig.  166. 
Scale  24  in.=l  in. 


spaced  twice  as  far  apart.  By  this  means  the  strength  of  the  middle  rivets 
is  reinforced  by  the  outside  rows.  As  the  middle  rivets  are  near  together, 
they  thus  make  a tight  joint  at  *?'and  fy  whereas  if  the  outside  welt,  b , was 
made  as  wide  as  a , there  would  be  difficulty  in  keeping  the  edges  on  the 
outside  tight  on  account  of  the  great  distance  apart  of  the  outer  rivets. 

QUESTION  267.  What  is  the  strength  of  butt  seams  or  -ioints  compared 
with  those  which  have  been  described? 


208 


Catechism  of  the  Locomotive. 


Answer.  A butt  seam  with  double  strips  and  quadruple  rows  of  rivets 
is  little,  if  any,  stronger  than  a double-riveted  lap  seam  properly  propor- 
tioned. The  resistance  to  the  crushing  action  of  the  rivets  limits  the 
strength  of  both  kinds  of  seams,  and  in  that  respect  they  may  be  nearly 
equally  strong. 

Question  268.  What  other  advantages  have  butt  seams  with  double 
welts,  as  shown  in  figs.  163-166? 

Answer.  Such  seams  are  often  used  for  the  longitudinal  seams  of  boil- 
ers because  a lap  seam  like  that  shown  in  fig.  167,  when  subjected  to  a 
tensile  strain,  will  tend  to  draw  into  the  form  shown  in  fig.  168 — that  is, 


Bending  Action  on  Lap  Seam.  Scale  in.=l  in. 


the  tendency  is  to  draw  into  a straight  line,  and  a bending  strain  will  be 
exerted  on  the  plates  at  a and  b.  This  strain  also  tends  to  pull  the  plates 
apart  where  they  lap  over  each  other,  whereas  in  seams  like  those  shown  in 
figs.  163-166,  the  strain  on  the  plates  and  on  the  covering  strips,  a and  b , 
is  in  a line  parallel  with  their  surfaces,  and  therefore  no  bending  action  is 
exerted  on  them.  It  is  found  by  experience  that  boilers  are  very  often 
corroded  along  the  edges  of  the  plates  of  lap  seams  just  where  the  bend- 
ing action  takes  place.  It  is  probable  that  when  iron  or  steel  is  subjected 
to  a high  degree  of  tension,  and  at  the  same  time  exposed  to  substances 
which  corrode  them,  that  the  action  of  the  latter  is  most  rapid  where  the 
strain  is  greatest.  At  any  rate,  it  is  found  that  much  less  corrosion  occurs 
with  butt  seams  which  have  double  welts  than  with  lap  seams. 

Question  269.  What  are  the  proportions  commonly  used  for  butt 
seams  ? 


Locomotive  Boilers. 


209 


Answer.  The  following  table  is  from  Wilson’s  “ Treatise  on  Steam 
Boilers,”  and  gives  the  proportions  for  double-riveted  butt  seams  which 
are  very  commonly  used  : 

PROPORTIONS  FOR  BUTT  SEAMS  WITH  DOUBLE  STRIPS  AND  TWO 
ROWS  OF  RIVETS. 


Thickness  of  Plate. 

Diameter  of  Rivet. 

Thickness  of  Strip. 

Pitch  of  Rivets. 

% inch. 

% inch. 

inch. 

inch. 

7 “ 

n> 

% “ 

14  44 

2%  “ 

M 44 

% “ 

TB 

2M  44 

TB 

TB  41 

i5s 

2%  “ 

% “ 

H “ 

% 44 

3 

tt  “ 

94  44 

% U 

m 44 

H 44 

% 44 

TB 

314  44 

U “. 

% 44 

TB  ” 

316  44 

% 44 

l 

M 44 

3%  " 

n “ 

l 

V2  44 

3M  44 

i 

44 

TB 

4 

Question  270.  How  should  a quadruple-riveted  butt  seam  with  double 
strips  of  maximum  strength  be  proportioned? 

Answer.  The  diameter  and  pitch  of  rivets  should  be  proportioned  in 
the  same  way  as  for  a double-riveted  lap  seam.  A butt  seam  has  usually 
an  excess  of  rivet  area  to  resist  shearing,  because  the  rivets  are  subjected 
to  a double  shear.  The  strength  of  such  a seam  is,  however,  limited  by 
the  resistance  of  the  metal  in  front  of  the  holes  to  crushing.  There  is, 
therefore,  not  much  difference  in  the  strength  of  well-proportioned  double- 
riveted  lap  and  butt  seams. 

Question  271.  What  influence  does  the  size  of  the  rivet-heads  and  ends 
have  on  the  strength  of  a seam  ? 

Answer.  It  has  been  found  that  an  increase  of  about  one-third  in  the 
weight  of  the  rivets  (all  this  increase  going  to  the  heads  and  ends)  was 
found  to  add  about  8|-  per  cent,  to  the  resistance  of  the  joint.  Rivets, 
BEFORE  THEIR  HEADS  ARE  FORMED,  SHOULD  PROJECT  BEYOND  THE 
PLATES  A DISTANCE  EQUAL  TO  ABOUT  THREE  TIMES  THEIR  DIAMETERS 
TO  GIVE  SUFFICIENT  MATERIAL  FOR  THE  HEADS. 

Question  272.  What  practical  consideration  must  govern  the  propor- 
tions of  riveted  seams  ? 


210 


Catechism  of  the  Locomotive. 


A?tswer.  It  must  be  determined  what  is  the  greatest  pitch  of  rivets 
which  can  be  used  in  any  particular  case.  Generally  it  becomes  a question 
of  how  wide  a pitch  can  be  used  and  the  boiler  be  made  tight  by  caulking. 
The  proportions  for  riveted  seams  given  in  the  tables  are  such  as  have 
been  extensively  used  in  practice.  With  improved  material  and  work- 
manship, doubtless  larger  rivets  than  the  sizes  given  in  the  tables  can  be 
used,  and  they  can  be  spaced  farther  apart  and  still  make  a tight  joint, 
and  a nearer  approximation  can  be  made  to  the  dimensions  given  by  the 
rules  for  proportioning  seams  of  maximum  strength. 

Question  273.  How  are  the  seams  of  boilers  made  tight  ? 

Answer.  By  what  is  called  caulking — that  is,  by  the  use  of  a blunt 
instrument,  A,  fig.  169,  somewhat  resembling  a chisel,  the  end,  a,  of  which 


Fig.  170.  Method  of  Caulking  Seams.  Scale  % in.=l  in. 


is  placed  against  one  of  the  edges  of  the  plate,  B,  which  is  then  compressed 
or  riveted  down  by  blows  of  a hammer,  somewhat  as  the  joints  between 
the  planks  of  a ship  are  made  tight.  The  edges,  e,  of  the  plates — called 
the  caulking  edges — are  sometimes  planed  before  they  are  put  together, 
but  more  commonly  they  are  cut  or  trimmed  off  with  a chisel.  In  this 
process  the  plate  is  often  injured  seriously  by  the  carelessness  of  workmen, 
who  sometimes  allow  the  chisel  to  cut  a groove  in  the  plate  at  C,  under 
the  edge,  thus  weakening  it  at  a point  where  the  greatest  strength  is 


Locomotive  Boilers. 


211 


needed.  If  driven  too  hard  the  tool  is  liable  to  force  the  plates,  £ and  C, 
apart,  as  indicated  by  the  dotted  line  below  B.  For  these  reasons  Mr. 
Connery,  foreman  of  the  boiler-shop  at  the  Baldwin  Locomotive  Works  in 
Philadelphia,  devised  a system  of  caulking  with  a tool,  D,  having  a round 
nose,  a',  as  shown  in  fig.  170.  With  this  there  is  no  liability  to  groove  the 
lower  plate  nor  force  the  plates  apart. 

Question  274.  How  much  water  is  usually  carried  in  a locomotive 
boiler  ? 

Answer.  There  must  always  be  enough  water  in  the  boiler  to  cover 
completely  all  the  parts  which  are  exposed  to  the  fire,  otherwise  they  will 
be  heated  to  so  high  a temperature  as  to  be  very  much  weakened  or  per- 
manently injured.  In  order  to  be  sure  that  all  the  heating  surface  will  at 
all  times  be  covered  with  water,  it  is  usually  carried  so  that  its  surface  will 
be  from  4 to  8 inches  above  the  crown-sheet. 

QUESTION  275.  How  much  space  should  there  be  over  the  water  for 
steam  ? 

Answer.  No  exact  rule  can  be  given  to  determine  this.  It  may,  how- 
ever, generally  be  assumed  that  the  more  steam  space  the  better.  In 
order  to  increase  the  steam  room,  locomotive  boilers  are  very  generally 
made  in  this  country  with  what  is  called  a wagon-top , V,  fig.  121 — that 
is,  the  outside  shell  of  the  boiler  over  the  fire-box  is  elevated  at  V,  from 
4 to  12  or  even  18  inches  above  the  cylindrical  part. 

QUESTION  276.  What  is  a steam-dome , and  for  what  purpose  is  it  in- 
tended? 

Answer.  A steam-dome , U U,  fig.  121,  is  a cylindrical  chamber  made 
of  boiler-plate  and  attached  to  the  top  of  the  boiler.  Its  object  is  to  in- 
crease the  steam  room  and  to  furnish  a reservoir  which  is  elevated  con- 
siderably above  the  surface  of  the  water,  from  which  the  supply  of  steam 
to  be  used  in  the  cylinders  can  be  drawn.  The  reason  for  drawing  the 
steam  from  a point  considerably  above  the  water  is  that  during  ebullition 
more  or  less  spray  or  particles  of  water  are  thrown  up  and  mixed  with  the 
steam.  When  this  is  the  case,  steam  is  said  to  be  wet,  and  when  there  is 
little  or  no  unevaporated  water  mixed  with  it,  it  is  said  to  be  dry.  It  is 
found  by  experience  that  wet  steam  is  much  less  efficient  than  that  which 
is  dry.  There  is  also  danger  that  the  cylinders,  pistons,  or  other  parts  of 
the  machinery  may  be  injured  if  much  water  is  carried  over  from  the 
boiler  with  the  steam,  because  water  will  be  discharged  so  slowly  from 
the  cylinders  that  there  is  not  time  when  the  engine  is  running  fast  for  it 
to  escape  before  the  piston  must  complete  its  stroke,  so  that  the  cylinder- 


212 


Catechism  of  the  Locomotive. 


heads  will  be  “ knocked  out,”  or  the  cylinder  itself,  or  the  piston  will  be 
broken.  The  reason  for  drawing  or  “ taking  ” steam  from  a point  con- 
siderably above  the  water  is  because  there  is  less  spray  there  than  there  is 
near  the  surface,  and  the  hottest  steam,  which  is  also  the  dryest,  ascends 
to  the  highest  part  of  the  steam  space. 

Question  277.  Where  is  the  dome  usually  placed? 

Answer.  In  this  country  it  is  usually  placed  over  the  fire-box,  but  in 
Europe  it  is  often  placed  further  forward,  either  about  the  centre  of  the 
boiler  or  near  the  front  ends  of  the  tubes. 

Question  278.  How  is  the  steam  conducted from  the  dome  to  the  cyl- 
inders ? 

Answer.  By  a pipe,  T O'  O , fig.  121,  called  the  dry-pipe,  which  extends 
from  the  top  of  the  dome  to  the  front  tube-plate.  On  the  front  side  of 
the  tube-plate  and  inside  the  smoke-box  two  curved  pipes,  84  84,  fig.  98, 
called  steam-pipes,  are  attached  to  the  dry-pipe  at  one  end,  and  to  the 
cylinders  at  the  other.  The  vertical  portion,  Q,  of  the  dry-pipe  in  the 
dome,  sometimes  called  the  throttle-pipe,  is  usually  made  of  cast  iron,  the 
horizontal  part  of  wrought  iron,  and  the  steam-pipes  of  cast  iron. 

Question  279.  How  is  the  loss  of  heat  from  locomotive  boilers  by  radia- 
tion and  convection  prevented? 

Answer.  Usually  by  covering  the  boiler  and  dome  with  wood,  called 
lagging,  about  inch  thick,  which  is  a poor  conductor  of  heat,  and  then 
covering  the  outside  of  the  wood  with  Russia  iron,  the  smooth,  polished 
surface  of  which  is  a poor  radiator  of  heat.  Sometimes  locomotive  boilers 
are  first  covered  with  felt  and  then  with  wood  and  Russia  iron.  Recently 
plastic  material,  which  hardens  after  it  is  applied  to  the  boiler,  has  been 
used  a good  deal.  This  is  also  covered  with  Russia  iron. 

Question  280.  What  is  the  smoke-box  for? 

Answer.  The  smoke-box,  B,  fig.  121,  is  simply  a convenient  receptacle 
for  the  smoke  before  it  escapes  into  the  chimney  or  smoke-stack,  which  is 
attached  to  the  top  of  the  smoke-box.  It  also  affords  a convenient  place 
for  the  steam  and  exhaust-pipes,  where  they  are  surrounded  with  hot  air 
and  smoke,  and  not  exposed  to  loss  of  heat  by  radiation. 

Formerly  smoke-boxes  were  made  without  the  portion  shown  in  fig. 
121,  which  extends  in  front  of  the  ring,/.  This  part,  called  the  extended 
front  end,  has  been  added  to  give  room  for  appliances  to  arrest  the  sparks. 
These  consist  of  a deflector,  F,  in  front  of  the  tubes  and  wire  netting,/^, 
which  cause  the  heavy  sparks  and  cinders  to  be  thrown  forward,  and  pre- 
vent them  from  being  carried  up  the  chimney.  They  are  thus  deposited 


Locomotive  Boilers. 


213 


in  the  front  end,  from  which  they  can  be  removed  by  a suitable  aperture, 
Z,  at  the  bottom. 

The  front  of  the  smoke-box  is  usually  made  of  cast  iron,  with  a large 
door,  M,  in  the  centre,  which  affords  access  to  the  inside. 

QUESTION  281.  How  are  the  chimneys  or  smoke-stacks  of  locomotives 
constructed? 

Answer.  The  forms  of  smoke-stacks  which  have  been  used  are  almost 
numberless.  When  an  extended  front-end,  such  as  is  shown  in  fig.  121,  is 
used,  the  chimney  often  consists  of  merely  a straight  pipe,  D,  as  repre- 
sented. A larger  drawing  of  this  stack  is  given  in  fig.  171.  For  burning 


or  Chimney.  or  Chimney. 


bituminous  coal  and  wood,  what  is  called  a diamond  stack — probably  from 
the  shape  of  the  outline  of  the  top — as  shown  in  fig.  172,  is  used  a great 
deal.  This  consists  of  a central  pipe,  4 1,  and  a conical-shaped  cast-iron 
plate,  3,  called  the  cone  or  spark  deflector , which,  as  the  latter  name 


214 


Catechism  of  the  Locomotive. 


implies,  is  intended  to  deflect  the  motion  of  the  sparks  and  cinders  which 
are  carried  up  with  the  ascending  current  of  smoke  and  air  in  the  pipe,  1, 
so  as  to  prevent  them  from  escaping  into  the  open  air  while  they  are  in- 
candescent, or  “ alive.”  A wire  netting,  4 5,  is  also  provided,  which  is 
intended  as  a sort  of  sieve  to  enclose  the  sparks  and  cinders,  and  at  the 
same  time  allow  the  smoke  to  escape.  The  receptacle  below  the  cone  is 
intended  as  a chamber  in  which  the  burning  cinders  will  be  extinguished 
before  they  escape.  For  burning  anthracite  coal,  a simple  straight  pipe, 
as  shown  in  fig.  171,  without  a deflector  or  wire  netting,  is  ordinarily  used. 
For  burning  wood  a chimney  or  smoke-stack  of  the  form  shown  in  fig. 
172  is  sometimes  used,  but  more  generally  one  of  the  form  shown  in  fig. 
173,  which  is  a wide  stack,  with  a straight  interior  pipe,  8,  a cone,  3,  and 


Fig.  173.  Wood  Burning  “ Smoke-Stack”  or  Chimney. 


wire  netting,  5.  Inside  the  outer  shell,  G,  there  is  an  inner  box  or  bonnet, 
7.  The  sparks  collect  in  the  space  outside  the  straight  pipe,  8,  and  can 
be  removed  through  the  hand-hole,  9. 


Locomotive  Boilers. 


215 


QUESTION  282.  What  are  the  proportions  and  materials  usually  em- 
ployed in  the  construction  of  smoke-stacks  ? 

Answer.  The  pipe,  6,  fig.  171,  is  usually  made  of  the  same  inside 
diameter  as  the  cylinders,  or  an  inch  or  two  smaller.  For  the  other  di- 
mensions there  are  no  established  rules,  excepting  for  the  height  of  the 
top  of  the  chimney  above  the  rail,  which  is  usually  from  14  to  15  feet. 
The  outside  of  smoke-stacks  are  made  of  sheet  iron,  but  the  upper  part  is 
now  sometimes  made  of  cast  iron,  so  as  to  withstand  the  abrasion  of  the 
sparks  and  cinders  longer  than  sheet  iron  will.  For  very  warm  and  damp 
climates,  the  outsides  of  smoke-stacks  are  sometimes  made  of  copper  to 
resist  corrosion,  which  is  very  destructive  to  all  iron  structures  in  those 
countries.  The  wire  netting  is  made  of  iron  or  steel  wire  from  to 
inch  in  diameter,  and  with  from  8 to  4 meshes  to  the  inch. 


CHAPTER  XIII. 


THE  BOILER  ATTACHMENTS. 

QUESTION  283.  How  is  water  supplied  to  the  boiler  to  replace  that  which 
is  converted  into  steam  ? 

Answer.  It  is  forced  into  the  boiler  against  the  steam  pressure  by  a 
force  or  feed  pump,  or  by  an  instrument  called  an  injector. 

Question  284.  How  is  a feed  pump  constructed  and  what  is  the  prin- 
ciple of  its  operation  ? 

Answer.  The  ordinary  single-acting  pump,  fig.  174,  used  on  locomotive 
and  other  steam-engines,  consists  of  a pump-barrel,  A A,  which  is  a cast 
iron  or  brass  cylinder  in  which  a tight-fitting  piston,  B B,  called  the  pump- 
plunger,  works.  This  piston  or  plunger  is  simply  a round  rod  which 
works  air-tight  through  a stuffing-box , C,  the  construction  of  which  is 
similar  to  that  used  in  piston-rods  and  described  in  answer  to  Question 
95.  The  plunger  is  usually  connected  to  the  cross-head,  and  receives  a 
reciprocating  motion  from  it,  but  sometimes  the  plunger  is  worked  by  a 
small  crank  attached  to  one  of  the  crank-pins  or  by  an  eccentric  on  one 
of  the  axles.  The  pump-barrel  is  connected  with  the  water-tank  of  the 
tender  by  the  suction.pipe,  D,  and  with  the  water-space  of  the  boiler  by 
the  feed  pipe,  E E.  Over  the  suction-pipe,  D,  is  a valve,  F,  called  the 
suction-valve,  which  opens  upward,  and  below  the  feed  pipe,  E,  is  another 
valve,  G,  called  the  pressure-valve.  These  valves  are  cylindrical  or  of 
the  form  of  an  inverted  cup.  They  are  made  of  brass,  and  rest  on 
brass  seats,  g g',  to  which  they  are  fitted  so  as  to  be  water-tight.  They 
work  in  guides,  k k,  called  cages,  the  form  of  which  is  more  clearly  shown 
in  the  sectional  plan,  fig.  176.  When  the  plunger  is  drawn  out  of  the 
pump-cylinder  it  creates  a vacuum  behind  it,  and  the  pressure  above  the 
valve,  G,  closes  it,  while  the  atmospheric  pressure  on  the  water  in  the 
tank  forces  it  into  the  suction-pipe,  D,  opens  the  valve,  F,  and  fills  the 
pump-cylinder.  When  the  plunger  is  forced  back  again  the  force  with 
which  it  presses  against  the  water  in  the  pump-barrel,  A,  closes  the  valve, 
F,  and  lifts  the  pressure-valve,  G,  and  the  water  is  then  forced  through 
the  feed  pipe  into  the  boiler.  In  order  to  be  certain  that  the  water  in  the 


The  Boiler  Attachments. 


217 


Section  of  Pump.  Scale  1 in.=l  ft. 


218 


Catechism  of  the  Locomotive. 


boiler  will  not  flow  back  into  the  pump,  and  also  to  prevent  all  the  water 
and  steam  in  the  boiler  from  escaping  in  case  of  accident  to  either  the 
feed  pipe  or  pump,  another  valve,  H,  called  a check-valve , is  placed 
between  the  feed  pipe  and  the  boiler.  The  construction  of  this  valve  is 
similar  to  that  of  the  pressure  and  suction-valves.  It  is  enclosed  in  a cast 
iron  or  brass  case,  II.  All  of  these  valves  have  cages  or  guides  in  which 
they  work  and  which  also  act  as  stops,  to  prevent  them  from  rising  from 
their  seats  further  than  a certain  distance.  This  distance  is  called  their 
lift , and  the  successful  working  of  the  pumps  depends  very  much  on  the 
amount  of  lift  which  the  valves  have.  This  is  usually  from  to  \ inch. 
The  valves,  G and  H,  are  represented  open  and  the  darts  at  g show  the 
directions  of  the  flow  of  the  water.  The  valve,  F,  is  shown  closed. 

Over  the  pressure- valve,  G,  is  a chamber,  J , called  an  air-chamber. 
When  water  is  forced  into  this  chamber,  it  is  obvious  that  as  soon  as  it 
rises  above  the  mouth  of  the  pipe,  E,  the  air  above  the  surface  of  the 
water  will  be  confined  in  this  chamber.  This  confined  air,  being  elastic, 
will  be  compressed  and  expanded  by  the  pressure  of  the  water,  so  that  it 
forms  a sort  of  cushion,  which  relieves  the  pump  and  the  pipes  from  the 
sudden  shocks  to  which  they  are  subject,  owing  to  the  rapid  motion  of 
the  pump-plunger. 

Another  air-chamber,  K , is  sometimes  placed  below  the  suction-valve, 
F.  The  object  of  this  is  to  supply  a cushion  to  relieve  the  suction-pipe 
from  the  shock  which  is  caused  by  the  sudden  arrest  of  the  motion  of  the 
water  in  the  pipe,  D,  when  the  valve,  F,  is  closed.  When  the  pump-plunger 
is  drawn  out,  the  water  flows  up  through  the  valve,  F,  to  fill  the  vacuum 
in  the  pump-barrel,  A A,  and  consequently  all  the  water  in  the  suction- 
pipe  is  put  in  motion.  As  soon  as  the  plunger  returns,  the  valve,  F,  is 
closed  and  the  motion  of  the  water  is  suddenly  arrested,  thus  producing 
more  or  less  of  a shock  in  the  pipe,  D.  When  the  water  in  the  air- 
chamber,  K,  rises  above  the  mouth  of  the  pipe,  L,  it  is  evident  that  the 
air  above  that  line  will  be  confined  in  the  space  surrounding  the  pipe. 
This  air  then  forms  a cushion  in  the  same  way  as  that  in  the  upper  air- 
chamber,  J,  does,  which  has  already  been  explained. 

QUESTION  285.  How  can  the  pump  be  taken  apart  and  the  valves 
examined? 

Answer.  By  removing  the  nuts,  e e,  on  the  bolts  by  which  the  pump-barrel, 
A A,  and  the  air-chamber,  J,  are  held  together,  they  can  be  taken  apart,  and 
the  valve,  G,  and  cage,  k,  can  then  be  removed.  In  the  same  way,  by 
removing  the  nuts,/" f,  the  lower  chamber,  K,  can  be  detached  from  A A, 


The  Boiler  Attachments. 


219 


and  the  valve,  F,  and  cage,  k',  can  be  taken  out.  The  check-valve,  H, 
can  be  taken  out  by  removing  the  nuts,  / 1',  which  hold  up  the  valve-seat, 
k,  and  also  the  valve  and  cage. 

QUESTION  286.  To  what  risk  is  a check-valve  like  that  shown  in  jig. 
174  exposed? 

Answer.  In  case  of  a collision  or  other  accident  it  may  be  broken  off, 
and  the  hot  water  then  escapes  from  the  boiler,  and  is  liable  to  scald  per- 
sons who  cannot  escape  from  the  wreck.  In  several  instances  many 
persons  were  scalded  to  death  and  others  terribly  injured  in  this  way. 

Question  287.  How  can  the  danger  of  such  accidents  be  lessened? 

Answer.  By  putting  the  check-valve  inside  the  boiler  instead  of  outside. 
Fig.  177  shows  a check-valve  of  this  kind.  A A is  the  boiler  plate,  and  B 
B is  a cast  iron  flange  cast  in  one  piece  with  the  valve-seat,  C.  The  flange 
is  bolted  or  riveted  to  the  outside  of  the  boiler,  and  the  seat  is  let  into 
the  inside  through  an  opening  cut  into  the  boiler  plate.  D is  a flap-valve 


F 


Fig.  177.  Inside  Check-Valve. 


which  covers  the  opening  in  the  seat.  Its  position  when  open  is  indicated 
by  the  dotted  lines.  F is  an  elbow  pipe  screwed  into  the  casting  B B, 
and  is  connected  with  the  pump  or  injector.  In  case  of  an  accident,  if 


220 


Catechism  of  the  Locomotive. 


this  elbow  pipe  is  broken  the  valve  will  still  keep  its  opening  closed  and 
prevent  the  escape  of  the  hot  water  from  the  boiler.  This  or  some  similar 
safeguard  against  the  terrible  accidents  which  sometimes  result  from 
injury  to  check-valves  should  be  generally  adopted. 

Question  288.  How  can  it  be  known  whether  the  pump  is  forcing 
water  into  the  boiler  ? 

Answer.  To  show  this  a cock,  called  a pet-cock , j,  fig.  174,  is  attached 
to  the  upper  air-chamber  or  to  the  feed  pipe.  By  opening  this  cock,  if 
the  pump  is  working,  a strong  jet  of  water  will  be  discharged  from  it  dur- 
ing the  backward  stroke  of  the  pump-plunger.  If  the  pump  is  not  forcing 
water  into  the  boiler,  or  is  working  imperfectly,  the  stream  discharged 
from  the  pet-cock  will  be  weak,  and  the  backward  and  forward  strokes  of 
the  plunger  will  not  be  very  definitely  indicated  by  the  discharge  from 
the  pet-cock. 

Another  small  cock,  called  a frost-cock,  is  often  attached  to  the  lower 
air-chamber,  or  to  the  feed  pipe,  to  allow  the  water  in  them  to  escape 
in  cold  weather,  when  the  engine  is  not  working,  so  as  to  prevent  it  from 
freezing  and  bursting  the  pipe  or  pump. 

Question  289.  Why  is  it  necessary  to  be  able  to  regulate  the  quantity 
of  water  which  is  forced  into  the  boiler  by  the  pump  ? 

Answer.  Because  when  the  engine  is  working  hard — that  is,  in  start- 
ing or  pulling  a heavy  load  up  a grade,  more  steam  and  consequently  more 
water  are  consumed  than  when  it  is  not  working  so  hard,  and  therefore 
more  water  must  be  forced  in  to  supply  the  place  of  that  which  is  used  in 
the  form  of  steam.  If  more  water  is  forced  in  than  is  consumed,  the  water 
will  rise  and  fill  the  steam  space,  and  a part  of  it  will  then  be  carried  into 
the  cylinders  without  being  evaporated.  If  too  little  water  is  forced  into 
the  boiler,  the  heating  surface  will  not  be  covered,  and  there  will  conse- 
quently be  danger  that  those  portions  which  are  exposed  to  the  fire  will 
be  overheated  and  injured. 

Question  290.  How  is  the  supply  of  water  which  is  fed  into  the  boiler 
by  the  pump  regulated  ? 

Answer.  By  a cock  in  the  suction-pipe  called  a feed-cock,  which  can  be 
regulated  by  the  locomotive  engineer,  so  that  more  or  less  water  is  sup- 
plied to  the  pump.  There  is  also  a valve  in  the  water-tank,  the  con- 
struction of  which  is  explained  in  Chapter  XXIV,  by  which  the  supply 
of  water  can  be  regulated. 

Question  291.  On  what  part  of  the  locomotive  are  the  pumps  usually 
placed ? 


The  Boiler  Attachments. 


221 


Answer.  They  are  usually  attached  to  the  frames  behind  the  cylinders, 
and  are  connected  to  the  cross-head,  as  has  been  explained  ; but  they  are 
sometimes,  but  rarely,  placed  inside  of  the  frames — that  is,  between  the 
wheels,  and  worked  from  an  eccentric  on  one  of  the  axles,  and  sometimes 
they  are  placed  outside  of  the  wheels  near  the  back  part  of  the  locomo- 
tive, and  worked  from  short  cranks  attached  to  the  crank-pins  although 
this  plan  is  now  seldom  employed.  Pumps  have  now,  to  a very  great 
extent,  been  displaced  by  injectors  for  feeding  boilers. 

Question  292.  What  provision  is  made  for  preventing  the  water  in 
the  pumps , pipes  and  tank  from  freezing  in  cold  weather  ? 

Answer.  Pipes  which  communicate  with  the  steam-space  of  the  boiler 
are  attached  to  each  of  the  suction-pipes,  so  that,  by  opening  the  valves 
in  the  former,  steam  is  admitted  into  the  suction-pipes  to  heat  the  water 
in  them*  By  admitting  this  hot  water  into  the  pump  and  tank,  it  is 
kept  warm,  and  the  water  is  thus  prevented  from  freezing. 

Question  293.  What  is  an  “ injector  ” ? 

Answer.  It  is  an  instrument  in  which  a jet  of  steam  imparts  its  velocity 
to  water,  and  thus  forces  it  into  the  boiler  against  the  pressure  of  the 
steam. 

Question  294.  What  are  the  principles  of  the  action  of  an  injector  ? 

Answer.  The  action  of  an  injector  is  due  to  the  fact  that  the  velocity 
of  steam  which  escapes  from  the  boiler  at  a given  pressure  is  very  much 
greater  than  that  of  water  under  the  same  conditions.  If  water  is  brought 
in  contact  with  a jet  of  steam,  the  latter  will  impart  its  velocity  to  the 
water,  and  by  mixing  with  it  the  steam  will  be  condensed. 

Question  295.  How  is  an  injector  co7istructed ? 

Answer.  Fig.  178  represents  what  maybe  called  a rudimentary  form  of 
an  injector.  B is  a boiler  and  W a water-tank.  A is  a pipe  to  carry 
steam  from  the  boiler  to  the  injector,  and  C one  for  supplying  it  with 
water,  and  D another  pipe  to  conduct  the  water  to  the  boiler.  The  end 
of  the  pipe,  A,  terminates  with  the  nozzle,  F,  in  the  inside  of  a cone,  E , 
on  the  end  of  the  pipe,  C.  When  steam  is  admitted  to  the  pipe,  A,  by 
opening  the  valve,  K,  it  escapes  from  the  nozzle,  F,  and  the  lower  end  of 
E,  and  the  current  of  steam  creates  a partial  vacuum  in  the  cone,  E and 
in  C.  The  water  is  thus  sucked  up  from  the  tank,  W , and  flows  through 
the  pipe,  C,  into  E,  where  it  meets  the  current  of  steam  escaping  from 
E.  This  carries  part  of  the  water  with  it,  and  they  escape  at  e.  Below  E 

* Injectors  are  now  made  so  that  the  steam  can  be  admitted  through  them  to  the  heater 
pipes. 


222 


Catechism  of  the  Locomotive. 


there  is  another  tube,  G,  which  is  connected  to  the  boiler  by  the  pipe,  D, 
and  has  a valve,  H,  which  is  raised  up  by  the  pressure  of  the  water  below 
it  in  the  pipe,  D,  and  it  thus  closes  the  lower  end  of  G so  that  no  water 
can  escape  from  the  boiler  through  the  pipe,  D.  It  will  be  noticed  that 
there  is  some  space  at  e between  the  lower  end  of  E and  the  top  of  G. 
When  steam  is  admitted  to  F,  as  has  been  explained,  it  sucks  the  water 


up  the  pipe,  C,  and  forces  it  out  at  e.  When  the  stream  of  steam  meets 
the  water  in  E,  the  steam  imparts  its  velocity  to  the  water,  but  in  mixing 
with  it  the  steam  is  condensed  so  that  the  jet,  which  escapes  from  E,  is 
composed  of  water  alone.  This  at  first  escapes  from  e,  but  after  flowing 
a few  seconds  its  velocity  and  momentum  become  so  great  that  it  forces 
the  valve,  H,  down,  and  the  jet  of  water  then  flows  into  the  boiler  against 
the  pressure  of  the  steam.  As  soon  as  the  injector  ceases  to  work,  the 
check-valve,  H,  is  closed  by  the  pressure  of  the  water  below  it,  so  that  no 
water  can  escape  from  the  boiler.  This  diagram  has  been  given  only 
to  illustrate  the  principles  of  the  injector,  and  it  should  be  understood 
that  it  does  not  represent  an  actual  working  instrument. 

Question  296.  How  is  the  operation  of  the  injector  explained f 


The  Boiler  Attachments. 


223 


Answer.  The  escaping  steam  from  the  nozzle,  F,  unites  with  the  feed- 
water  in  the  cone,  E,  and  gives  to  this  water  a velocity  greater  than  it 
would  have  if  escaping  directly  from  the  water-space  in  the  boiler.  The 
power  of  this  water  to  enter  the  boiler  comes  from  its  weight  moving  at 
the  velocity  acquired  from  the  steam,  and  its  momentum  thus  enables  it 
to  overcome  the  boiler  pressure. 

This  can  be  illustrated  with  a wooden  ball,  which  will  float  on  the  sur- 
face of  water  and  will  require  some  force  to  make  it  sink,  but  if  it  is  thrown 
violently  into  the  water,  it  will  sink  to  a considerable  depth  before  its 
buoyancy  will  overcome  its  momentum,  or  actual  energy.  If,  however,  we 
were  to  take  a cork  or  very  light,  hollow  wooden  or  india-rubber  ball,  no 
matter  how  violently  we  throw  it  into  the  water,  it  will  not  sink,  because 
the  total  actual  energy  of  the  body  IS  proportional  TO  its  weight 
MULTIPLIED  BY  the  square  OF  its  velocity,  and,  therefore,  if  we  throw 
the  hollow  ball  at  the  same  velocity  as  the  solid  one,  the  former  will  still 
have  much  less  energy  than  the  latter.  Now,  as  already  stated,  steam  un- 
der a given  pressure  escapes  from  an  orifice  with  a very  much  greater 
velocity  whan  water.  But  steam  being  very  light,  if  its  weight  is  multi- 
plied by  its  velocity  its  total  energy  will  be  comparatively  small.  But  in 
an  injector,  a portion  of  the  high  velocity  of  the  steam  is  imparted  to  the 
heavy  water,  because  this  water  is  presented  to  the  action  of  the  steam, 
not  in  a mass,  as  in  the  boiler,  but  in  small  quantity  and  in  such  a position 
that  it  can  easily  escape,  so  that  it  gradually  acquires  as  high  a velocity  as 
the  escaping  steam  can  impart,  and  at  the  same  time  the  steam  is  condensed, 
and  therefore  there  is  a heavy  substance  with  a high  velocity,  whose  actual 
energy  is  sufficient  to  overcome  the  pressure  in  the  boiler.  If  the  steam 
were  not  condensed  we  would  have  a comparatively  light  substance  mov- 
ing at  a high  velocity,  which,  as  has  already  been  explained,  would  have 
little  actual  energy,  and  would  therefore  not  overcome  the  boiler  pressure. 

Question  297.  Will  the  injector  feed  hot  water  ? 

Answer.  The  instrument  will  not  work  when  the  feed-water  is  too  hot 
to  condense  the  steam,  for  the  reasons  given  above,  and  the  amount  of 
water  thrown  is  always  the  greatest  when  the  feed-water  is  the  coldest. 
Steam  at  a low  pressure  can  be  condensed  more  readily  than  steam  of  higher 
pressure,  because  it  contains  less  heat.  The  feed-water  may  be  used  hot- 
ter to  condense  low  steam  than  to  condense  high  steam.  In  using  the 
injector,  the  lower  the  boiler  pressure  the  hotter  may  be  the  water  within 
certain  limits,  the  limit  being  the  possible  condensation  of  the  steam, 

Question  298,  How  are  injectors  constructed? 


224 


Catechism  of  the  Locomotive. 


Answer.  The  simplest  form  of  injector  which  is  made  is  that  shown  in 
fig.  179,  in  which  all  the  details  of  construction  are  omitted.  In  this  the 
nozzle,  F,  called  the  steam-nozzle , the  cone,  E,  called  the  combining-tube, 
and  the  pipe,  G,  called  the  delivery-tube , are  all  fixed.  In  this  the  steam 
from  the  boiler,  passing  through  the  pipe,  A,  enters  the  steam-nozzle , F. 
Here  it  is  joined  by  the  water  which  enters  the  pipe,  C.  The  water  con- 
denses the  steam  in  the  combining-tube,  E,  and  a water  jet  is  formed  which 
is  driven  across  the  overflow  space,  e e,  and  enters  the  delivery-tube,  G, 


thence  past  the  check-valve , H,  into  the  boiler.  During  the  passage  of  the 
water  from  E to  G,  as  it  passes  across  the  overflow  space,  e e,  if  too  much 
water  has  been  supplied  to  the  steam,  some  will  escape  at  this  point  and 
flow  out  through  the  overflow  nozzle,  O,  while  if  too  little  water  has  been 
supplied,  air  will  be  drawn  in  at  O,  and  carried  into  the  boiler  with  the 
water. 

QUESTION  299.  Is  a fixed  nozzle  injector,  such  as  has  been  described, 
well  adapted  as  a boiler  feeder  in  locomotives  ? 


The  Boiler  Attachments. 


225 


Answer.  It  will  work  very  well  within  a small  range  of  steam  pressures, 
but  if  the  boiler  pressure  rises  above  that  for  which  the  tubes  are  especi- 
ally adapted,  the  capacity  and  range  of  the  instrument  are  proportionately 
decreased.  On  the  other  hand  with  lower  steam  pressures,  the  injector 
will  waste  at  the  overflow  unless  readjusted  by  careful  handling  of  the 
“ lazy  cock.” 

Question  300.  What  is  required  in  an  injector  to  adapt  it  to  work 
satisfactorily  at  different  steam  pressures  ? 

Answer.  The  instrument  must  be  so  made  that  the  water  passage 
between  the  steam-nozzle  and  the  combining-tube  can  be  varied  in  size 
automatically  or  by  hand.  This  is  usually  done  by  making  the  steam- 
nozzle  and  combining-tube  conical  and  moving  the  former  to  or  from  the 
latter,  thus  contracting  or  enlarging  the  water-space.  Such  adjustment 
must  be  made  at  each  change  of  steam  pressure  in  the  boiler. 

Question  301.  Is  it  essential  that  injectors  should  be  in  a vertical  posi- 
tion, as  shown  in  figs.  178  and  179  ? 

Answer . No.  Injectors  will  work  equally  well  in  any  position.  For 
convenience  they  are  usually  attached  to  locomotives,  so  that  their  axis 
or  centre  lines  stand  horizontal. 

Question  302.  What  different  forms  of  injectors  are  used? 

Answer.  A great  variety  of  these  instruments  are  made,  only  a few  of 
which  will  be  illustrated  and  described. 

Figs.  180  and  181  represent  an  outside  view  and  section  of  a self-acting 
injector  manufactured  by  Messrs.  William  Sellers  & Co.  (incorporated), 
of  Philadelphia.  It  consists  of  a case,  A,  fig.  181,  provided  with  a steam 
inlet,  B,  a water  inlet,  C,  an  outlet,  D,  through  which  the  water  is  con- 
veyed to  the  boiler,  an  overflow  opening,  E,  a lever,  F,  by  which  to  admit 
steam,  start  and  stop  its  working,  a hand  wheel,  G,  to  regulate  the  supply 
of  water,  and  an  eccentric  lever,  H,  to  close  the  waste-valve,  L , when  it  is 
desired  to  make  a heater  of  the  injector. 

The  operation  of  the  injector  is  as  follows : The  water  inlet,  C,  being 
in  communication  with  the  water-supply,  the  valve,  a , is  opened  by  turn- 
ing the  wheel,  G,  to  allow  the  water  to  enter  the  chamber,  I.  Steam  is 
admitted  to  the  chamber,  B,  and  the  lever,  F,  is  operated  to  lift  the  valve, 
b , slightly  from  its  seat.  This  permits  steam  to  enter  the  annular  lifting 
steam-nozzle,  c , through  the  holes,  d d,  while  the  plug,  i,  attached  to  the 
valve,  h,  still  fills  and  keeps  the  tube,  K,  closed.  The  steam  issuing  from 
the  nozzle,  c,  passes  through  the  annular  combining-tube,  e,  and  escapes 
from  the  instrument  partly  through  the  overflow  opening,/,  and  partly 


226 


Catechism  of  the  Locomotive. 


through  the  overflow  openings  provided  in  the  combining-tube,  g gf, 
through  the  overflow-chamber,  J,  and  passage,  E E,  and  produces  a 
strong  vacuum  in  the  water-chamber,  /,  into  which  the  water  from  the 


Fig.  180.  Sellers’  Injector. 


source  of  supply  is  forced  by  air  pressure,  and  the  united  jet  of  steam  and 
water  is,  by  reason  of  its  velocity,  discharged  into  the  combining-tube,^. 
The  spindle,  h , is  now  withdrawn  by  the  lever,  E,  until  the  steam  plug, 
/,  is  out  of  the  forcing  nozzle,  K,  thus  allowing  the  steam  to  pass  through 
the  forcing  nozzle,  K,  and  come  in  contact  with  the  annular  jet  of  water 
which  is  flowing  into  the  combining-tube  around  the  nozzle,  K.  This  jet 
of  water  has  already  considerable  velocity,  and  the  forcing  steam  jet  im- 
parts to  it  the  necessary  increase  of  velocity  to  enable  it  to  open  the  valve, 
k,  and  thus  enter  the  boiler  through  the  pipe,  D. 

If  from  any  cause  the  jet  should  be  broken — say  from  a failure  in  the 
water-supply — the  steam  issuing  from  the  forcing  nozzle,  K , into  the  com- 
bining-tube,  g,  will  escape  through  the  overflows,  m and  n,  and  inter- 


The  Boiler  Attachments. 


227 


mediate  openings  with  such  freedom  that  the  steam  which  returns  through 
the  annular  space  formed  between  the  nozzle,  K,  and  combining-tube,  g, 
and  escapes  into  the  overflow-chamber  through  the  opening,  /,  will  not 
have  sufficient  volume  or  force  to  interfere  with  the  free  discharge  of  the 
steam  issuing  from  the  annular  lifting  steam-nozzle  and  escaping  through 
the  same  overflow,/,  and  hence  the  lifting  jet  will  always  tend  to  produce 


Fig.  181.  Section  of  Sellers’  Injector. 


a vacuum  in  the  water-chamber,  I,  which  will  again  lift  the  water  when 
the  supply  is  renewed,  and  the  combined  annular  jet  of  steam  and  water 
will  be  forced  into  the  combining-tube,  g,  against  the  feeble  current  of 
steam  returning,  when  the  jet  will  again  be  formed  and  will  enter  the 
boiler  as  before. 

If  the  overflow  valve,  L,  is  closed  by  the  lever,  H,  and  steam  is  then 
admitted  by  opening  the  valve,  b,  there  will  be  no  outlet  for  the  steam 
excepting  into  the  chambers,  J and  /,  and  if  the  valve,  a,  is  open  the  steam 
will  flow  into  the  pipe,  C,  and  thence  back  to  the  water-tank.  Therefore, 
if  it  is  necessary  to  turn  steam  into  the  supply-pipe  or  tank  to  prevent 
them  from  freezing,  it  can  be  done  by  closing  the  valve,  L,  and  opening 
the  valves  a and  b. 


328 


Catechism  of  the  Locomotive. 


Fig.  182.  “ Monitor  ” Injector. 


TO  BOILER. 


The  Boiler  Attachments. 


229 


Figs.  182  and  188  represent  the  “ Monitor  ” injector,  made  by  the 
Nathan  Manufacturing  Company,  of  New  York.  It  consists  of  a body,  B, 
fig.  188,  made  in  two  parts  and  provided  with  the  usual  inlets  for  steam  and 
water,  at  A and  C,  and  with  a delivery  end,  D.  It  is  further  provided  with 
a lifting  steam-valve,  /,  which  is  worked  by  a handle,  L ; a forcing  steam- 
valve,  S,  worked  by  the  handle,  N,  and  a water-valve,  f,  worked  by  a 
handle,  M.  The  handle,  O,  serves  for  closing  the  waste-valve  when  it  is 
desired  to  use  the  injector  as  a heater. 


Fig'.  184.  Mack’s  Injector. 


Fig.  185.  Section  of  Mack’s  Injector. 

The  operation  of  the  injector  is  as  follows : The  water-valve,  f,  being 
open,  and  the  steam  inlet,  A,  in  communication  with  the  boiler,  the  valve, 
/,  is  opened.  This  operation  will  admit  steam  into  the  tube,  t,  which 
flows  through  the  nozzles,  n n' , into  the  atmosphere,  and  creates  a partial 
vacuum  in  the  water-chamber,  W.  Water  is  thus  drawn  from  the  supply- 
tank  into  the  chamber,  IV,  and  is  discharged  into  the  combining-nozzle, 
E,  and  through  openings  in  this  combining-tube  into  and  out  through  the 
passage,  n n',  and  overflow  at  e.  As  soon  as  the  water  appears  at  e,  the 


230 


Catechism  of  the  Locomotive. 


valve,  S,  is  opened  and  the  valve,  /,  is  closed.  The  steam  issuing  from  the 
nozzle,  F,  meets  the  water  in  the  nozzle,  F,  and  imparts  to  it  sufficient  force 
and  velocity  to  open  the  check-valve,  H,  and  discharge  the  fluid,  at  D , 
into  the  pipes  leading  to  the  boiler.  The  supply  is  regulated  by  the  water- 
valve,/. 


OVERFLOW 

Fig.  186.  Hancock  Inspirator. 


The  lifting  apparatus  in  this  injector,  it  will  be  seen,  is  separate  from 
and  independent  of  the  forcing  nozzles,  and  has  a free  discharge  into  the 
atmosphere.  The  forcing  nozzles  are  all  fixed  nozzles,  plain  in  construe- 


The  Boiler  Attachments. 


231 


tion,  with  large  and  unobstructed  water  ways.  The  parts  can  easily  be 
removed,  and  as  the  lifting  as  well  as  the  forcing  nozzles  are  in  straight 
lines,  small  obstructions  can  be  removed  by  passing  a wire  through  them. 
Figs.  184  and  185  represent  Mack’s  injector,  manufactured  by  the 


National  Tube  Works  Company,  of  Boston.  From  the  preceding  descrip- 
tion its  construction  and  operation  will  be  readily  understood.  The  parts 
can  be  easily  removed  and  cleaned,  or  renewed  if  worn  by  the  action  of 
impure  water. 

Figs.  186  and  187  represent  outside  and  sectional  views  of  the  Hancock 


232 


Catechism  of  the  Locomotive. 


Inspirator,  made  by  the  Hancock  Inspirator  Company,  of  Boston.  In  this 
the  lifting  and  forcing  jets  and  nozzles  are  independent  of  each  other.  A, 
fig.  187,  is  the  steam-supply  pipe,  B is  the  water-supply  pipe,  C is  the  feed 
pipe  leading  to  the  boiler,  and  O is  the  overflow.  D is  the  lifting  jet,  E 
the  lifting  nozzle,  G the  forcing  jet,  and  H the  forcing  nozzle.  F is  a slide- 
valve  which  governs  the  admission  of  steam  to  the  nozzles.  I is  an  over- 
flow valve  for  the  lifting  side  of  the  injector,  and  J a similar  valve  for  the 
forcing  side.  In  fig.  186  a lever  and  handle  is  shown  by  which  the  working 
of  the  instrument  is  controlled.  Two  positions  of  this  lever  are  repre- 
sented by  the  dotted  centre  lines,  a b c and  a'  b c' , in  fig.  187.  It  is  connect- 
ed to  a fixed  pivot  or  fulcrum,  b , and  at  its  lower  end  to  a short  lever, 
pivoted  at  d , shown  in  fig.  186,  and  represented  by  the  centre  lines,  a d 
and  a'  d,  in  fig.  187.  This  lever  has  a short  arm,  indicated  by  the  dot- 
ted line,  e d f,  on  its  lower  end  and  connected  to  the  overflow  valves,  I 
and  J.  Above  the  fulcrum,  b,  the  lever,  a b c,  is  connected  to  another 
lever  shown  in  fig.  186,  and  represented  by  the  centre  lines,  g h / and  g' 
h /',  in  fig.  187,  and  which  is  pivoted  at  h. 

When  steam  and  water  are  shut  off,  the  long  lever  and  handle  stand  in 
the  position  shown  in  fig.  186,  and  indicated  by  the  dotted  line,  a b c,  in 
fig.  187.  The  valve,  F,  then  covers  both  the  steam-ports,  j and  k,  and 
the  two  overflow  valves,  / and  J,  are  both  open.  When  the  upper  end,  c, 
of  the  lever,  a b c,  is  moved  toward  the  left,  the  action  of  the  lever,  g h z, 
moves  the  valve,  F,  toward  the  right,  which  uncovers  the  steam-port,/, 
and  admits  steam  into  the  chamber,  K ; this  steam  flows  through  the  jet, 
F),  and  the  nozzle,  F,  which  produces  a partial  vacuum  in  L,  which  com- 
municates with  M,  and  water  is  thus  drawn  up  through  the  pipe,  B,  and 
is  carried  along  by  the  jet  and  escapes  through  the  overflow  valve,  /,  into 
the  chamber,  B,  and  thence  through  the  passage,  O.  After  a current  is 
thus  established  the  lever,  a be,  is  moved  still  farther  toward  the  left-hand 
side,  which  closes  the  valve,  /,  and  the  water  then  fills  the  chamber,  N, 
and  rises  until  it  reaches  the  top  of  the  nozzle,  H.  The  upper  end  of  the 
lever,  a be,  is  moved  still  farther  toward  the  left,  which  moves  the  valve, 
F,  so  as  to  admit  steam  to  the  port,  k,  and  chamber,  Q.  This  steam 
flows  through  the  jet,  G,  and  nozzle,  H,  and  carries  the  water  in  the  cham- 
ber, R,  with  it  into  the  chamber,  S,  from  which  it  escapes  through  overflow 
valve,  J,  and  pipe,  O.  After  the  current  is  established  the  upper  end  of 
the  lever,  a b c,  is  moved  still  farther  to  the  left,  which  closes  the  valve, 
J,  and  the  water  is  then  forced  from  the  chamber,  S,  through  the  check- 
valve,  V,  and  pipe,  C,  into  the  boiler. 


The  Boiler  Attachments. 


233 


Fig.  188.  Korting’s  Universal  Injector. 


Fig.  189.  Section  of  Korting’s  Universal  Injector. 


234 


Catechism  of  the  Locomotive. 


The  action  of  the  instrument  is  thus  controlled  by  the  movement  of  the 
one  lever.  A valve  for  regulating  the  supply  of  water  is  attached  to  the 
pipe,  B,  but  is  not  shown  in  the  engraving. 

Figs.  188  and  189  represent  the  “Universal  Double  Tube  Injector,” 
made  by  L.  Schutte  & Co.,  of  Philadelphia.  As  will  be  observed  from 
fig.  189,  there  is  a combination  of  two  steam  jets  in  this  instrument.  The 
first  or  lower  one,  E,  is  proportioned  as  an  ejector,  that  is,  an  instrument 
which  will  give  suction  but  discharges  against  a moderate  pressure  only. 
It  takes  water  through  the  supply  pipe,  B,  and  chamber,  M,  from  which 
it  is  discharged  through  the  tube,  E,  into  the  second  chamber,  L Z, 
which  communicates  with  the  combining  tube,  H,  of  the  second  or  upper 
apparatus,  which  is  the  injector  proper,  and  is  proportioned  to  feed 
against  the  high  pressure  in  the  boiler.  In  this  way  the  first  tube  acts  as 
a feeder  to  the  injector  proper,  and  its  duty  is  to  supply  automatically  the 
water  required  by  the  injector  proper  at  different  steam  pressures.  The 
volume  of  the  discharge  of  the  lower  tube,  E,  is  diminished  when  the 
pressure  in  the  chamber,  Z,  is  reduced,  and  vice  versa ; therefore,  if  the 
upper  tube,  H,  takes  the  discharge  from  L rapidly  it  reduces  the  pressure 
therein  and  thus  increases  the  supply  from  the  tube,  E,  while  if  the 
discharge  from  E is  greater  than  is  required  by  the  upper  tube,  H,  the 
pressure  in  L is  increased  which  reduces  the  volume  of  water  supplied 
by  E. 

The  two  tubes  are  so  proportioned  and  adjusted  to  each  other  that  a 
small  pressure  is  always  maintained  in  the  chamber,  Z,  so  that  the  upper 
tube  always  receives  its  supply  under  pressure.  The  advantage  of  this  is 
that  the  temperature  of  the  feed-water  can  be  correspondingly  high.  In 
starting,  the  lower  tube  discharges  free  into  the  atmosphere  through  the 
outlet,  O. 

The  injector  is  started  and  stopped  by  moving  the  lever,  c , in  the  direc- 
tion indicated  by  the  dart.  This  opens  the  lower  steam  vaive,  j,  which 
produces  a current  of  steam  through  the  tube,  E,  and  draws  water  from 
the  supply  branch,  B,  and  discharges  it  through  the  overflow  passage,  O. 
Continuing  the  movement  of  the  lever  and  it  partially  closes  the  overflow 
valve,  J,  and  the  chamber,  Z,  is  then  filled  with  water  which  flows  through 
the  tube,  H , of  the  second  injector,  and  through  the  centre  of  the  over- 
flow valve.  Further  movement  of  the  lever  opens  the  upper  steam  valve,  k, 
and  closes  the  overflow  valve,  J,  entirely,  and  the  instrument  then  forces 
water  to  the  boiler  through  the  pipe,  C.  These  operations  are  performed 
without  stop  and  by  one  continuous  slow  movement  of  the  starting  lever. 


The  Boiler  Attachments. 


235 


Question  303.  What  attachments  are  needed  in  connection  with  an 
injector  to  make  it  effective  ? 

Answer.  A valve  should  be  placed  in  the  pipe  by  which  the  injector  is 
supplied  with  steam.  This  valve  is  to  be  closed  only  when  there  is  occa- 
sion to  remove  the  injector  when  steam  is  up,  and  in  cold  weather,  to 
prevent  the  condensation  of  steam  in  the  pipes  at  the  end  of  its  trips. 
During  the  time  that  the  injector  is  working  this  valve  should  be  wide 
open. 

Question  304.  In  what  position  are  injectors  usually  placed? 


190-  Fig.  191. 

Location  of  Injector  on  End  of  Boiler. 

Answer.  They  are  put  inside  the  cab,  usually  on  the  side  of  the  boiler, 
in  a position  where  they  can  be  easily  inspected  by  the  locomotive  runner. 
A check-valve  similar  to  that  shown  in  connection  with  the  pump  in  fig. 
174,  is  attached  to  the  front  part  of  the  boiler  and  the  feed-pipe  of  the 
injector  is  connected  to  it.  A better  arrangement,  and  one  which  is  not 


236 


Catechism  of  the  Locomotive. 


liable  to  the  danger  to  which  a check-valve  in  such  a position  is  exposed, 
and  which  has  been  described,  is  in  common  use  in  European  engines  and 
on  the  Canadian  Pacific  Railway,  and  is  represented  by  fig.  190,  which  is 
a view  of  the  back  end  of  the  boiler,  and  fig.  191,  which  is  a longitudinal 
section  of  that  part  of  the  boiler.  The  injectors,  A and  B,  are  placed  ver- 
tically and  are  attached  to  the  boiler.  The  feed  pipe  is  connected  directly 
to  the  boiler,  and  is  carried  forward  inside  of  it,  and  discharges  the  water 
at  its  front  end.  By  this  means  neither  the  check-valve  nor  the  feed-pipe 
are  exposed  to  injury  in  case  of  accident,  nor  to  frost  in  cold  weather. 
The  steam  pipe,  D,  for  supplying  steam  to  the  injector  is  also  placed  in- 
side of  the  boiler.  On  the  outside  of  the  boiler  the  pipes  are  very 
unsightly,  besides  being  exposed  to  injury. 

Question  305.  What  is  required  to  keep  an  injector  in  good  working 
order  ? 

Answer . Constant  use  is  better  than  occasional  use.  When  there  are 
two  injectors  on  an  engine,  one  on  each  side,  the  one  on  the  engineer’s 
side  should  be  used  while  running,  and  the  other  one  when  the  engine  is 
standing  still.  All  pipe  connections  should  be  tight  so  as  to  prevent  the 
leaking  of  air.  The  pipe  which  conveys  steam  to  the  instrument  should 
take  its  supply  from  such  part  of  the  boiler  as  will  insure  the  use  of  dry 
steam,  and  the  waste-pipe  must  not  be  contracted. 

Question  306.  How  can  the  height  of  the  water  in  the  boiler  be 
known  ? 

Answer . Two  appliances  are  used  by  which  the  height  of  the  water  in 
the  boiler  can  be  observed.  These  are  : 1.  Gauge  or  try-cocks . 2.  A glass 
water-gauge. 

Every  locomotive  is  provided  with  three  or  more  gauge-cocks,  which 
are  usually  placed  at  the  back  end  of  the  boiler  where  they  can  easily  be 
seen  and  reached.  These  cocks,  S S S,  are  shown  in  fig.  192,  which 
represents  a longitudinal  section  of  the  end  of  the  boiler,  and  fig.  193, 
which  is  an  end  view  of  the  cocks.  The  position  of  these  cocks  is  also 
shown  at  94,  in  fig.  99.  They  communicate  with  the  inside  of  the  boiler 
and  are  so  placed  that  one  is  3 or  4 inches  above  the  other.  The  upper 
cock  is  placed  above  the  point  where  the  surface  of  the  water  should  be 
when  the  engine  is  working,  and  the  lower  one  below  it,  so  that  the  upper 
one  communicates  with  the  steam-space  and  the  lower  one  with  the  water. 
When  these  cocks  are  opened,  if  the  water  is  at  its  proper  height,  steam 
is  discharged  from  the  upper  one,  and  water  from  the  lower  one. 

When  a gauge-cock  which  communicates  with  the  steam-space  is  first 


The  Boiler  Attachments. 


237 


opened,  it  is  usually  filled  with  condensed  water,  so  that  it  should  gener- 
ally be  kept  open  for  a little  while  until  this  water  is  discharged.  If  the 
upper  cock  is  opened  and  continues  to  discharge  water,  it  indicates  that 
there  is  too  much  water  in  the  boiler ; on  the  other  hand,  if  steam  is  dis- 
charged when  the  lower  cock  is  opened,  then  there  is  too  little  water  in 
the  boiler,  and  the  heating  surface  is  in  danger  of  being  exposed  to  the 
fire  without  being  covered  with  water,  and  consequently  Overheated,  or, 
as  it  is  called,  “burned,”  and  so  injured  as  to  become  too  weak  to  bear 
the  strain  to  which  it  is  subjected  by  the  pressure  of  the  steam.  There  is 
then  great  danger  that  the  crown-sheet  may  be  crushed  down  by  the 
pressure  of  the  steam  above  it,  or  that  the  boiler  may  be  exploded.  Even 
if  no  accident  occur,  the  boiler  is  in  great  danger  of  permanent  injury 
from  overheating  when  the  water  is  allowed  to  get  too  low. 


Below  the  gauge-cock,  figs.  192  and  193,  a receptacle,  R,  called  a drip , 
is  placed  to  receive  the  water  and  steam  which  are  discharged  from  the 
cocks.  This  water  is  conducted  away  by  the  pipe,  T. 

The  water-gauge , fig.  194,  also  shown  at  104,  fig.  99,  consists  of  an 


238 


Catechism  of  the  Locomotive. 


upright*  glass  tube,  a a,  which  is  from  % to  £ inch  in  diameter,  and  from  12 
to  15  inches  long.  The  glass  is  about  £ inch  thick.  At  its  ends  it  com- 
municates with  the  steam  and  water  of  the  boiler  through  brass  elbows, 


b c.  The  openings  in  these  elbows,  which  communicate  with  the  boiler, 
are  closed  by  the  valves  or  plugs,  d and  e , which  are  worked  by  screws 


* Sometimes  these  tubes  are,  for  convenience,  inclined. 


The  Boiler  Attachments. 


239 


and  handles,  f g.  The  glass  tube,  when  it  is  attached  to  the  elbows,  is 
made  steam-tight  by  rubber  rings,  which  are  pressed  tight  around  the  tube 
by  packing-nuts,  h and  i.  The  elbows  are  provided  with  the  valves,  d and 
e , so  that  in  case  the  glass  tube  breaks  the  steam  and  water  can  be  shut 
off,  so  as  not  to  escape  through  the  elbows.  The  lower  elbow  is  provided 
with  a blow-off  cock,  k,  through  which  any  sediment  or  dirt  which  collects 
in  the  glass  tube  or  elbows  can  be  blown  out.  When  the  valves  in  the 
upper  and  lower  elbows  are  opened  the  steam  flows  into  the  glass  tube 
through  the  upper  one,  and  water  through  the  lower  one,  and  the  water 
assumes  a position  in  the  glass  tube  on  a level  with  the  surface  of  that  in 
the  inside  of  the  boiler — thus,  the  position  of  the  water  in  the  boiler  becomes 
visible  in  the  glass  tube.  On  account  of  the  constant  variations  of  the  water 
in  the  boiler,  the  column  of  water  in  the  glass  never  remains  stationary,  but 
plays  up  and  down  as  long  as  the  boiler  is  working.  But  if  the  communi- 
cation between  the  glass  tube  and  the  boiler  is  closed,  then  the  water  in 
the  tube  becomes  stationary  and  the  water-gauge  is  useless.  In  order 
that  there  may  be  no  obstruction  of  the  glass  tube  by  mud  or  dirt  from 
the  water,  it  must  be  blown  out  often.  To  do  this  the  lower  valve,  e , is 
closed,  and  the  blow-off  cock,  k,  and  the  steam-valve,  d , are  opened.  The 
steam  pressure  in  the  tube  on  top  of  the  column  of  water  will  force  it  out 
of  the  blow-off  cock,  and  the  mud  and  dirt  will  be  carried  with  it. 

If  from  any  cause  the  glass  tube  is  broken,  first  of  all  the  water-valve, 
e,  should  be  closed,  and  then  the  steam-valve,  df  so  as  to  prevent  the  hot 
water  and  steam  which  will  escape  from  the  broken  glass  from  scalding 
those  who  are  working  the  engine.  By  unscrewing  the  nuts,  h and  i,  the 
old  glass  can  easily  be  removed  and  a new  one  substituted  in  its  place. 
Care  should  be  taken  in  putting  in  new  glasses  not  to  screw  the  packing- 
nuts  down  any  more  than  just  sufficiently  to  make  the  rubber  rings  steam- 
tight  around  the  glass  tubes.  If  they  are  screwed  too  tight  they  are  apt 
to  produce  a strain  on  the  tube,  so  that  the  slightest  expansion  by  heat  or 
contraction  from  cold  will  break  it. 

Question  307.  What  safeguard  is  used  in  locomotives  to  guard 
against  the  danger  of  low  water  ? 

Answer.  What  are  called  safety-plugs  are  inserted  in  the  highest  part 
of  the  crown-sheet.  These  consist  of  hollow  brass  plugs,  fig.  195,  with  a 
cavity,  C,  in  the  centre,  which  is  filled  with  metal  that  melts  at  a low 
temperature.  The  plug  is  screwed  into  the  crown-sheet,  A A,  and  its 
lower  end  is  exposed  to  the  fire.  In  case  the  water  gets  low  and  the  plate 
dangerously  overheated,  the  fusible  metal  melts  and  runs  out  of  the  plug, 


240 


Catechism  of  the  Locomotive. 


so  that  steam  can  escape  through  it,  which  thus  gives  warning  of  the 
danger,  and  relieves  the  pressure  in  the  boiler. 

QUESTION  308.  How  is  the  steam  pressure  in  boilers  prevented  from  ex- 
ceeding a certam  limit  ? 

Answer.  By  what  are  called  safety-valves.  These  consist  of  circular 
openings,  shown  at  44,  Plate  IV,  about  3 inches  in  diameter,  placed  usually 
on  the  top  of  the  dome,  and  covered  by  a valve  which  is  pressed  down  by  a 
spring.  Two  of  these  valves  are  usually  placed  on  the  top  of  the  dome. 


so  that  if  one  gets  out  of  order  the  other  one  will  allow  the  steam  to 
escape  as  soon  as  its  pressure  exceeds  that  which  it  has  been  decided  the 
boiler  can  safely  bear.  This  pressure  in  locomotive  boilers  is  usually  from 
120  to  170  lbs.  per  square  inch.  One  of  these  valves  should  be  provided 
with  a lever  so  that  in  case  of  accident  or  other  cause  it  should  be  neces- 
sary to  relieve  the  steam  pressure  in  the  boiler,  there  will  be  some  means 
of  doing  it. 

Question  309.  How  is  the  amount  of  pressure  which  must  bear  on  top 
of  the  safety-valve  determined  ? 

Answer.  The  pressure  is  determined  by  multiplying  the  area  of 

THE  OPENING  FOR  THE  VALVE  IN  SQUARE  INCHES  BY  THE  GREATEST 
STEAM  PRESSURE,  IN  POUNDS  PER  SQUARE  INCH,  WHICH  THE  BOILER  IS 
intended  to  bear.  Thus,  if  the  opening  for  a safety-valve  is  3 inches 
in  diameter,  its  area  will  be  7 square  inches,  and,  therefore,  if  the  greatest 
steam  pressure  which  it  is  intended  that  the  boiler  shall  bear  is  150  lbs. 
per  square  inch,  the  valve  must  be  pressed  down  with  a pressure  equiva- 
lent to  7 x 150=1,050  lbs. 

Question  310.  How  are  safety-valves  co7istructed? 

Answer.  They  are  made  in  a variety  of  forms.  Fig.  196  represents  a 
section  of  Richardson’s  safety-valve,  which  is  now  very  generally  used. 
a is  the  valve  which  rests  on  the  seat,  b b.  c c'  is  a spindle,  the  lower  end 


The  Boiler  Attachments. 


241 


of  which  rests  on  the  bottom  of  the  hole  in  the  centre  of  the  valve,  a.  A 
spiral  spring,  in,  rests  on  a shoulder,  d,  on  the  spindle.  The  pressure  bn 
the  spring  is  regulated  by  the  nut,  n,  which  screws  to  the  case,  e.  This 
case  is  connected  by  ribs,/"  f,  to  the  outer  case,  g g,  into  which  the  seat, 
b b , is  screwed  at  h h.  The  valve  has  a grove,  i i,  around  its  outside  rim. 
As  the  valve  raises  it  compresses  the  spring,  which  increases  its  resistance, 
and  therefore  without  some  provision  to  obviate  this  difficulty  it  would 


Fig.  196.  Section  of  Richardson’s  Safety-Valve.  • 

be  raised  only  a very  short  distance  above  the  seat  after  steam  commenced 
to  blow  off.  For  this  reason  the  top,  a,  of  the  valve  is  made  considerably 
larger  in  diameter  than  the  opening  at  b b.  In  the  under  side  of  the  valve 
a grove,  / i,  is  turned.  When  the  valve  lifts,  this  grove  is  filled  with  steam, 
which  presses  against  that  portion  of  the  valve  outside  of  the  opening,  b b. 


242 


Catechism  of  the  Locomotive. 


which  causes  the  valve  to  raise  higher  and  remain  open  longer  than  it 
would  without  this  device.  A ring,  j,  is  screwed  to  the  outside  of  the 
seat,  b b.  This  can  be  screwed  up  or  down,  and  in  this  way  the  amount 
of  opening  around  the  edge  of  the  valve  can  be  regulated. 

The  valve  is  usually  fitted  into  a conical  seat,  shown  at  b b , so  as  to  be 
perfectly  steam-tight,  and  is  made  with  wings  or  guides.  These  guides 
are  intended  to  keep  the  valve  in  its  proper  position  in  relation  to  its  seat. 

Question  311.  What  precautio7i  must  be  taken  to  prevent  reckless  or 
ignorant  persons  fro77i  increasing  the  pressure  in  the  boiler  beyond  that  which 
it  is  thought  it  will  safely  bear  ? 


Fig.  197. 


Answer.  This  is  usually  done  by  arranging  one  of  the  safety-valves 
with  a lever  and  the  other  without.  The  latter  is  often  covered  and  sealed 
or  locked  up,  so  as  to  be  beyond  the  control  of  the  locomotive  engineer, 

Question  312.  How  can  it  be  known  that  the  safety-valves  are  in  good 
working  order  ? 

Answer.  The  one  which  has  a lever  should  be  frequently  opened,  as 
there  is  always  danger  that  the  safety-valve,  or  some  of  its  attachments, 
may  become  corroded  or  otherwise  disordered,  so  that  it  will  not  act 
promptly  or  with  certainty. 

Question  313.  How  is  the  fioise  of  the  stea7n  which  escapes  from  the 
safety-valve  dhninished  ? 

Answer.  By  what  are  called  mufflers.  These  are  constructed  in  a variety 
of  ways.  The  principle  on  which  they  all  act  is  to  subdivide  the  current 
of  steam,  into  many  small  streams,  which  reduces  its  noise.  Sometimes 
a vessel  is  filled  with  pebbles  or  glass  beads,  and  the  escaping  steam  is  made 
to  pass  among  them.  Figs.  196  and  197  show  the  arrangement  used  with 
Richardson’s  valve.  This  consists  of  a series  of  perforated  plates  or  discs, 
s s',  s s',  fig.  196,  -which  are  shown  in  a plan  view  in  fig.  197.  These  are 


The  Boiler  Attachments. 


24; 


placed  one  above  the  other,  with  a space  between  them.  The  steam  is 
thus  alternately  contracted  in  passing  through  the  holes  and  expanded  in 
the  spaces  above  them,  and  in  this  way  escapes  through  the  top  plate  with 
very  little  noise. 

Question  314.  How  is  the  steam  pressure  in  the  boiler  indicated? 

Answer.  By  an  instrument  called  a steam-gauge.  There  are  a great 
variety  of  such  instruments  made,  but  they  may  all  be  divided  into  two 
classes,  and  they  all  operate  upon  one  of  two  principles.  In  the  one  class 
the  pressure  of  the  steam  acts  upon  diaphragms  or  plates  of  some  kind, 
shown  in  fig.  198,  which  represents  a section  of  a pair  of  metal  plates,  A 
A,  of  this  kind.  These  are  made  with  circular  corrugations,  as  shown  in 
section  and  also  by  the  shading.  The  steam  enters  by  the  pipe,  c,  and 
fills  the  chamber  between  the  metal  plates  or  diaphragms.  The  corru- 


c 

Fig.  198.  Diaphragm  of  Steam-Gauge. 


gations  of  the  latter  give  them  sufficient  elasticity,  so  that  when  the  pres- 
sure is  exerted  between  them  they  will  be  pressed  apart  by  the  steam.  If 
they  were  flat,  it  is  plain  that  they  would  not  yield,  or  only  to  a very  slight 
degree,  to  the  pressure  of  the  steam. 

Fig.  199  represents  a view  of  a steam-gauge  of  this  kind,  with  its  face 
removed,  made  by  the  Utica  Steam-Gauge  Company.  The  diaphragms  are 
shown  just  below  a.  A bent  lever,  a , whose  fulcrum  is  at  c , bears  on  the 
diaphragm  at  a , and  is  connected  by  a short  rod,  o d,  to  another  bent 
lever,  b,  whose  fulcrum  is  at  e.  This  lever  has  a toothed  segment,  f g 
which  gears  into  a pinion  on  a spindle,  k.  This  spindle  carries  an  index 
hand  or  pointer,  h i.  It  is  plain  that  any  upward  movement  of  the  dia- 
phragm below  a will  lift  the  lever  o a c,  and  its  motion  will  be  communi- 
cated to  the  lever,  b,  and  by  the  segment  and  pinion  to  the  pointer,  and  it 
will  indicate  the  steam  pressure  on  a dial  similar  to  that  shown  in  fig.  201. 


244 


Catechism  of  the  Locomotive. 


Question  315.  What  other  kind  of  steam-gauge  is  used ? 

Answer.  In  the  other  class  of  gauges,  shown  in  figs.  201  and  202,  the 
steam  acts  upon  a bent  metal  tube,  a b c,  fig.  202,  of  a flattened  or  elliptical 
section.  It  may  not  be  known  to  all  readers  that  if  a tube  having  a 
section  of  that  form  is  bent,  say  in  the  shape  of  the  letter  U or  C.  and  is 
subjected  to  the  pressure  of  a liquid  or  gas  on  the  inside,  the  force  exerted 


Fig.  199.  Steam  Gauge. 


by  the  pressure  will  tend  to  straighten  out  the  tube.  This  is  due  to  the 
effect  of  pressure  on  the  inside  of  an  elliptical  or  flat  section,  which 
changes  its  shape  and  causes  it  to  approximate  to  a circular  form.  Thus 
let  A B,  fig.  200,  represent  a cross  section,  and  a b d c a longitudinal 
section  of  a part  of  such  a tube  contained  between  two  radii,  o a and  o b, 
drawn  from  the  centre,  o,  of  the  curve  in  which  the  tube  is  bent.  If  now 
we  subject  the  inside  of  A B to  a pressure  it  will  have  a tendency  to 
assume  the  form  of  the  circle  C D,  and  would  then  be  represented  in  the 
longitudinal  section  by  the  dotted  lines,  a'  b' d'  c\  If  we  draw  radial  lines 
through  a'  c’  and  b’ d’,  it  will  be  found  that  they  intersect  at  o'  instead  of 
o,  which  was  the  original  centre  of  the  curve  of  the  tube.  It  will  be  seen 
that  as  the  section  of  the  tube  approximates  to  the  form  of  a circle,  the 
side,  a b , which  is  outside  the  curve  will  be  moved  farther  from  the  centre, 


The  Boiler  Attachments. 


245 


while  the  other  side,  c d,  is  moved  nearer  to  it.  As  indicated  by  the  radial 
lines,  when  this  occurs  either  the  outside  must  be  lengthened  and  the 
inside  shortened,  to  conform  to  the  radial  lines,  a o and  b o,  or  else  the 
tube  will  be  straightened  so  that  the  radial  lines  will  assume  a'  o'  and  b'  o'. 


Fig.  200.  Diagram  Showing  Action  of  Steam  on  Bent  Tube. 

In  the  gauge  represented  in  figs.  202 — in  which  the  face  or  dial  plate  is 
removed — one  end,  c,  of  the  tube  is  attached  to  a bent  lever,  c f l in , 
which  is  connected  by  a rod,  g,  to  a toothed  segment,  e.  The  end,  a , 
of  the  tube  is  connected  to  the  lever  at  f.  It  is  obvious  that  as  the 
two  ends  of  the  bent  tube  are  forced  apart  by  the  steam  pressure,  the 
lower  end  of  the  lever  and  the  segment  will  be  moved  toward  the  left 
hand  side.  The  segment  gears  into  a pinion  on  the  spindle,  s,  which 


246 


Catechism  of  the  Locomotive. 


Fig.  201. 


Fig.  202.  Ashcroft  Steam-Gauge. 


The  Boiler  Attachments. 


247 


carries  the  index  or  pointer,  p p,  which  indicates  on  the  dial,  shown  in 
fig.  201,  the  degree  of  pressure  in  the  tube.  The  latter  is  connected  with 
the  boiler  by  a tube  attached  at  h.  The  gauge  shown  by  figs.  201  and  202 
is  made  by  the  Ashcroft  Manufacturing  Company,  of  New  York.  Various 
forms  of  this  kind  of  steam-gauge  are  made,  but  all  act  on  essentially 
the  same  principle. 

The  pipe  which  connects  the  steam-gauge  with  the  boiler  is  usually 
bent  to  prevent  the  hot  steam  from  coming  in  contact  with  the  metal 
plate  or  tube,  as  it  is  found  that  the  heat  of  the  steam  affects  their  elasti- 
city. When  a bent  tube  is  used,  the  steam  from  the  boiler  is  condensed 
and  fills  the  bent  portion  so  that  when  the  steam  pressure  comes  on  the 
surface  of  the  water  it  forces  it  up  the  other  leg  of  the  tube  into  the  gauge. 
A cock  is  attached  to  this  pipe  so  that  the  steam  can  be  shut  off  in  case 
the  gauge  should  get  out  of  order  or  require  to  be  removed  while  there 
is  steam  in  the  boiler. 

Question  316.  How  can  the  accuracy  of  a steam-gauge  be  tested? 

Answer.  When  the  gauge  is  in  good  working  order,  the  index  or  poin- 
ter moves  easily  with  every  change  of  pressure  in  the  boiler,  and  if  the 
steam  is  shut  off  from  the  gauge,  the  index  should  always  go  back  to  0. 
In  order  to  determine  the  accuracy  of  its  indications,  however,  it  should 
be  tested  with  a column  of  mercury,  This  consists  of  a long,  vertical  tube, 
terminating  at  its  base  in  a closed  vessel  filled  with  mercury.  The  gauge 
is  then  attached  to  the  top  of  this  vessel  and  water  or  oil  is  forced  into 
the  vessel  on  top  of  the  mercury  and  into  the  gauge.  A pressure  of  one 
pound  per  square  inch  will  force  up  the  column  of  the  mercury  2.04  inches, 
so  that  by  graduating  the  tube  into  spaces  that  distance  apart,  the  divis- 
ions will  indicate  the  pressure  in  pounds  per  square  inch.  Thus,  a pres- 
sure of  50  lbs.  would  force  up  the  column  of  mercury  102  inches,  and  with 
100  lbs.  pressure  the  column  would  rise  204  inches,  and,  therefore,  when 
the  mercury  reaches  thd£e  or  any  other  points,  the  steam-gauge,  if  it  is 
accurate,  should  indicate  equivalent  pressures. 

The  ordinary  steam-gauges  are  very  liable  to  get  out  of  order,  and  there- 
fore they  should  be  frequently  tested  to  ascertain  whether  their  indica- 
tions are  correct. 

QUESTION  317.  What  is  a steam-whistle,  and for  what  purpose  is  it  used? 

Answer.  A steam-whistle  shown  in  section  in  fig.  203,  consists  of  an 
inverted  metal  cup  or  bell,  A , made  usually  of  brass.  The  lower  edge  of 
this  cup  is  placed  immediately  over  an  annular  opening,  a a,  from  which 
the  steam  escapes  and  strikes  the  edge  of  the  cup  or  bell,  which  produces 


248 


Catechism  of  the  Locomotive. 


a deep  shrill  sound,  according  to  the  size  or  proportions  of  the  whistle. 
The  annular  opening,  a a , is  formed  by  the  plate  or  cover,  a a,  which 
nearly  fills  the  mouth  of  the  cup,  B,  which  is  attached  to  the  stem,  c. 
The  latter  is  screwed  into  the  top,  D , of  the  dome  of  the  boiler.  Com- 
munication with  the  steam-space  of  the  boiler  is  either  opened  or  closed 
by  a valve,  b,  which  is  attached  to  a sort  of  spindle,  d , which  extends  up- 
ward inside  of  the  stem,  c.  This  spindle  does  not  entirely  fill  the  opening 
in  the  stem,  c,  so  that  the  steam  which  enters  when  the  valve,  bt  is  opened 


rises  and  escapes  through  the  holes,  e e e,  into  the  cup,  B,  and  out  through 
the  annular  opening,  a a.  The  valve  is  opened  by  the  lever,  E,  whose 
fulcrum  is  at  f.  The  end,  g,  of  this  lever  is  connected  by  a rod,  h,  with 
the  cab,  and  by  a suitable  handle  or  lever  the  valve  can  be  opened  and  the 
whistle  be  blown  at  any  time  by  the  locomotive  runner  or  fireman  to  give 


The  Boiler  Attachments. 


249 


signals  to  the  trainmen,  or  of  the  approach  of  a train  to  the  station,  or  to 
warn  persons  to  get  off  the  track. 

Question  818.  How  is  a locomotive  boiler  emptied  and  cleaned? 

Answer.  One  or  two  large  cocks,  called  blow-off  cocks,  are  placed  near 
the  bottom  of  the  fire-box,  either  in  front  or  behind,  and  sometimes  on 
the  side.  By  opening  either  of  these  the  water  in  the  boiler  is  blown  out, 
and  much  of  the  loose  mud  and  dirt  is  carried  out  with  the  water. 

In  order  to  clean  out  the  mud  and  scale  which  are  not  entirely  loose, 
what  are  called  mud-plugs  ox  hand-holes  are  placed  in  the  corners  of  the 
fire-box  near  the  bottom.  The  former  are  screw-plugs,  which  can  easily 
be  unscrewed.  The  latter  are  oval-shaped  holes,  about  4-|-  inches  long  and 

inches  wide,  and  covered  with  two  metal  plates,  one  of  which  is  put  in- 
side the  boiler  and  the  other  outside,  and  fastened  with  a bolt  through 
both.  Another  hand-hole  is  sometimes  placed  at  the  bottom  of  the  front 
tube-sheet.  When  the  boiler  is  emptied  of  water  the  hand-holes  are 
opened  by  unscrewing  the  plugs  or  taking  off  the  covers,  and  as  much 
dirt  is  removed  as  can  be  scraped  out  of  these  holes.  A hose-pipe  is  then 
inserted  and  a strong  stream  of  water  is  forced  in,  which  washes  out  nearly 
all  the  loose  dirt,  so  as  to  leave  the  boiler  comparatively  clean. 

When  the  water  is  very  impure,  what  is  called  a mud-drum  is  some- 
times used.  This  is  a cylinder  of  wrought  iron  attached  to  the  under  side 
of  the  boiler  usually  near  the  smoke-box.  It  has  a cast-iron  cover  on  the 
bottom  which  can  be  removed  to  clean  it.  It  also  has  a blow-off  cock  to 
discharge  the  water  in  it.  Much  of  the  mud  and  dirt  is  deposited  in  this 
receptacle,  from  which  it  can  easily  be  removed  by  taking  off  the  cast-iron 
cover  or  blown  out  through  the  blow-off  cock. 

Question  819.  What  other  attachments  are  there  to  the  boiler  of  a 
locomotive  ? 

Answer.  There  is  a cock,  called  a blower-cock , attached  to  the  top  of 
the  boiler  and  connected  to  the  chimney  by  a pipe.  Steam  is  conducted 
through  this  pipe,  and  escapes  up  the  chimney  in  a jet,  thus  producing  a 
draft  when  the  engine  is  not  working.  This  arrangement  is  called  a blower , 
and  is  used  to  blow  the  fire  when  the  engine  is  standing  still.  The  action 
of  the  jet  is  similar  to  that  of  the  exhaust  steam  which  escapes  up  the 
chimney,  excepting  that  the  steam  from  the  jet  escapes  in  a continuous 
stream  instead  of  distinct  “puffs,”  as  it  does  when  it  is  liberated  alterna- 
tely from  one  end  of  the  cylinders  and  then  from  the  other. 

E,  fig.  121,  is  the  furnace  door,  which  is  fastened  by  a latch.  The  latter 
has  a chain  attached  to  it,  by  which  it  can  be  conveniently  opened  or  closed. 


250 


Catechism  of  the  Locomotive. 


Fig.  204.  Plan  of  Grate.  Scale  % in.=l  ft. 


•SOS  -3tj| 


* 


The  Boiler  Attachments. 


251 


Fig.  206. 

Longitudinal  Sections  of  Grate.  Scale  % in.=l  ft. 


252 


Catechism  of  the  Locomotive. 


Question  320.  How  arKe  the  grates  constructed? 

Answer.  As  has  already  been  explained,  they  are  made  usually  of  cast- 
iron  bars,*  AAA,  figs.  204  and  205,  called  grate-bars.  Fig.  204  is  a plan, 
and  fig.  205  a horizontal  section  of  one  form  of  grate.  The  bars  in  this 
kind  of  grate  are  usually  cast  in  pairs,  or  sometimes  three  or  more  are  cast 
together.  They  are  made  wider  on  the  top  than  on  the  bottom  edges,  as 
shown  in  the  section,  fig.  205,  so  that  cinders  and  ashes  will  fall  through 
easily,  and  also  to  give  free  access  to  the  air  from  below.  They  are  usually 
from  f to  1^  inch  wide  on  the  top,  and  about  f inch  on  the  lower  edges.  The 
spaces  between  the  bars  are  made  from  ^ to  inch  wide.  For  burning 
wood  the  bars  are  placed  comparatively  close  together  and  are  stationary 
but  for  burning  bituminous  coal  they  are  usually  made  so  that  they  can  be 
moved,  in  order  to  shake  or  stir  up  the  fire,  just  as  is  necessary  in  an 
ordinary  stove  or  grate  fire.  In  the  grate  we  have  illustrated,  the  bars, 
A A,  are  cast  in  pairs,  and  run  crosswise  of  the  fire-box.  The  ends  are 
made  with  a sort  of  journal,  b b,  fig.  204,  which  rest  on  supports,  B B, 
called  bearing-bars , which  have  suitable  indentations  to  receive  the  ends 
of  the  grate-bars.  The  latter  have  arms,  C C,  fig.  205,  cast  on  the  under 
side,  to  which  a bar,  D D , is  attached.  By  moving  this  bar  back  and 
forth,  the  grate-bars  have  a rocking  motion  imparted  to  them,  as  shown 
in  fig.  206.  It  is  evident  that  in  this  way  the  fire  over  the  whole  surface 
of  the  grates  will  be  disturbed  or  shaken.  The  bar,  D D,  is  moved  by  a 
suitable  lever  in  the  cab.  Grates  which  have  movable  bars  are  called 
shaking  or  rocking-grates.  A great  variety  of  such  grates  are  made  and 
in  use,  to  describe  which  would  require  more  room  than  is  available  here. 

For  burning  anthracite  coal,  what  are  called  water-grates  are  used,  see 
fig.  481.  These  consist  of  wrought-iron  tubes,  2 inches  in  diameter  out- 
side, which  are  fastened  in  the  front  and  back  plates  of  the  fire-box,  and 
are  inclined  upward  from  the  front  end,  so  that  there  will  be  a continued 
circulation  of  water  through  them  to  keep  them  cool  and  thus  prevent 
them  from  being  burned  out  by  the  intense  heat  of  the  fire. 

The  tubes  usually  have  about  four  solid  wrought-iron  bars  between  that 
number  of  tubes.  These  bars  can  be  withdrawn,  and  the  fire  then  falls 
into  the  ash-pan  through  the  opening  left  by  the  withdrawal  of  the  tubes. 

Question  321.  How  is  the  fire  re?noved  from  the  fire-box  when  it  is 
necessary  to  do  so  ? 

Answer.  In  bituminous  coal-burning  engines,  what  is  called  a drof- 

* In  Europe  generally,  and  in  some  few  cases  in  this  country,  the  grate-bars  are  made  of 
wrought-iron. 


The  Boiler  Attachments. 


253 


door,  E E,  figs.  204,  205  and  206,  is  provided  for  that  purpose.  This  door  is 
supported  partly  on  journals,  d d,  similar  to  those  in  the  grate-bars,  on 
which  it  can  turn,  and  is  held  up  or  prevented  from  dropping  by  arms,  e e, 
attached  to  a shaft,  F F.  This  shaft  is  operated  by  a lever,  ff,  fig.  204, 
outside  the  fire-box. 

When  the  arms  are  in  the  position  represented  in  fig.  205,  the  drop- 
door  is  held  up  in  the  place  in  which  it  is  shown ; but  when  they  are 
turned,  as  in  fig.  206,  the  door  falls  down  so  that  the  burning  coal  can  be 
taken  out  of  the  opening  at  G , and,  by  raising  up  the  ash-pan  damper,  H, 
can  be  raked  out  on  the  track  or  into  suitable  pits  usually  provided  for 
this  purpose.  The  drop-doors  are  sometimes  perforated  so  as  to  admit 
air  to  the  fuel  on  top  of  them. 

Question  322.  How  is  the  damper  of  the  ash-pan  operated? 

Answer. . It  is  connected  by  a rod  to  a bell-crank,  which  is  moved  by  a 
handle  in  the  cab  that  is  raised  or  lowered,  thus  opening  or  closing  the 
damper. 


CHAPTER  XIV. 


THE  THROTTLE-VALVE  AND  STEAM-PIPES. 

Question  323.  How  is  the  steam  admitted  to  and  the  supply  regulated 
or  shut  off from  the  cylinders? 

Answer.  By  a valve,  T,  fig.  121,  called  a throttle-valve,  which  is  usually 
placed  at  the  end  of  the  pipe,  O O'  Q,  near  the  top  of  the  dome.  Throttle- 
valves  are  sometimes  placed  in  the  smoke-box  at  the  front  end,  O,  of  the 
dry-pipe.  Until  within  a few  years  they  consisted  of  plain  slide-valves 
which  covered  openings  similar  in  form  to  the  steam-ports,  but  smaller  in 
size.  The  pressure  on  such  valves  wras  of  course  greatest  when  there  was 
no  steam  underneath,  which  was  the  case  when  the  valves  were  closed. 
It  was  then  very  difficult  to  open  them,  and  as  it  is  important  that  the 
supply  of  steam  admitted  to  the  cylinders  when  the  locomotive  is  started 
should  be  easily  regulated,  such  valves  were  objectionable,  and  therefore 
the  form  has  been  introduced  which  is  illustrated  in  fig.  121,  and  also  on 
a larger  scale  in  figs.  207  and  208,  which  represent  a longitudinal  section 
and  plan  of  the  throttle-pipe,  valve  and  throttle-lever.  The  valve,  T,  is 
what  is  called  a double-poppet  valve,  and  consists  of  two  circular  disks,  a 
and  b,  which  cover  two  corresponding  openings  in  the  case,  h,  on  the  end 
of  the  pipe,  Q.  When  these  disks  are  raised  up,  as  shown  in  fig.  207, 
steam  flows  in  around  their  edges,  as  represented  by  the  darts.  It  will  be 
observed  that  the  steam  pressure  in  the  boiler  comes  on  top  of  the  disk,  a, 
and  against  the  under  side  of  b.  The  pressure  on  the  one  thus  neutralizes 
or  balances  that  on  the  other.  If  the  two  disks  were  of  the  same  size,  the 
pressure  of  the  one  would  be  exactly  the  same  as  on  the  other ; but  as 
they  are  joined  together  and  are  made  to  fit  steam-tight  on  their  seats  by 
beveled joints,  their  diameters  must  be  somewhat  larger  than  the  openings 
they  cover.  The  only  practicable  way,  therefore,  by  which  the  lower  disk, 
b,  can  be  introduced  into  the  upper  end  of  the  pipe,  Q,  so  as  to  cover  the 
lower  opening,  is  through  the  upper  opening,  a.  For  this  reason  the 
lower  disk  must  be  made  smaller  than  the  upper  one,  and  therefore  the 
pressure  on  the  upper  one,  being  in  proportion  to  its  size,  it  is  in  excess  of 
that  on  the  lower  one  and  has  a constant  tendency  to  close  the  valve.  As 


The  Throttle-Valve  and  Steam-Pipes. 


255 


it  is  of  the  greatest  importance  that  a throttle-valve  should  remain  closed 
after  steam  is  shut  off,  and  never  be  opened  at  any  time  accidentally,  the 
arrangement  described  accomplishes  just  what  is  needed — that  is,  makes 
the  valve  work  comparatively  easy,  and  at  the  same  time  keeps  it  closed 
after  the  steam  has  been  shut  off. 

Question  324.  How  is  the  valve  opened  and  closed ? 

Answer.  By  a lever,  ABC,  called  a throttle-lever,  figs.  207  and  208.* 
This  lever  is  connected  by  a rod,  d B,  called  the  throttle-stem,  with  the 
lower  arm  of  a bell-crank,  dee,  the  other  arm  of  which  is  connected  by 
the  rod,  e f,  with  the  throttle-valve,  T.  The  rod,  d B,  works  through  a 
steam-tight  stuffing-box,  E,  in  the  back  end  of  the  boiler.  The  end  of 
the  throttle-lever  is  attached  to  a link,  D C,  fig.  208,  which  is  fastened  by 
a pin  to  the  stud,  D.  This  link  has  a slight  vibratory  motion,  which  en- 
ables the  pin,  B,  by  which  the  lever,  A B C,  is  fastened  to  the  rod,  d B, 
to  move  in  a straight  line,  which  is  necessary  in  order  that  the  rod  may 
work  steam-tight  in  the  stuffing-box,  E.  The  throttle-lever  has  a latch,  /, 
which  gears  into  a curved  rack,  n m,  so  has  to  hold  the  lever  and  valve  in 
any  required  position.  This  latch  is  operated  by  a trigger,  k,  which  is 
connected  to  the  latch  by  a rod,  r.  Various  other  devices  are  used  to 
fasten  throttle-levers  and  thus  hold  them  in  any  position  required. 

Question  325.  How  are  the  steam-pipes  constructed? 

Answer.  The  steam,  after  it  is  admitted  by  the  throttle-valve,  as  was 
explained  in  answer  to  Question  323,  passes  into  the  throttle-pipe,  Q,  and 
the  dry-pipe.  O'  O,  fig.  121.  At  the  front  end  of  the  dry-pipe,  a pipe,  O, 
which  divides  into  two  branches  like  the  top  of  the  letter  T,  and  is  there- 
fore called  a T-pipe,  is  attached.  This  pipe  is  indicated  by  number  85  in 
fig.  98.  The  steam-pipes,  84  84',  fig.  98,  are  connected  to  each  of  the  two 
branches  of  the  T-pipe  at  one  end  and  to  the  cylinder  castings  at  the 
other.f 

These  pipes,  being  in  the  smoke-box,  are  exposed  to  great  changes  of 
temperature,  and  are  therefore  subjected  to  expansion  by  heat  and  con- 
traction by  cold.  The  joints  are  therefore  constantly  liable  to  disturbance 
by  the  contraction  and  expansion  of  the  pipes,  and  so  are  difficult  to  keep 
tight.  It  is  also  practically  impossible  to  construct  the  boiler,  the  cyl- 
inders, and  the  pipes,  with  perfect  accuracy,  and  therefore  a small  amount 
of  adjustability  and  flexibility  is  necessary  in  the  joints  of  the  pipes.  If, 

* Fig.  208  shows  a plan  of  the  valve  and  lever. 

tin  fig.  98  the  right-hand  side  represents  a section  through  the  steam-pipe,  84  84',  and  the 
left  a section  through  the  exhaust-pipe,  80'. 


7H\ 


Fig.  £07. 


Tfnw 


The  Throttle-Valve  and  Steam-Pipes. 


257 


for  example,  the  upper  end  of  the  pipe,  84',  in  the  cylinder,  fig.  98,  were 
either  too  near  or  too  far  from  the  centre  of  the  engine,  it  would  be  neces- 
sary to  move  the  end  of  the  pipe,  84,  either  to  the  right  or  to  the  left  in 
order  to  connect  it  with  84'.  If  the  joint  of  the  upper  end  of  the  steam- 
pipe  were  attached  to  the  T-pipe,  with  a flat  joint  like  that  shown  at  a b, 
fig.  209,  it  would  be  impossible  to  move  the  lower  end  of  the  steam-pipe 


Fig.  209.  Steam-Pipe  Joint.  Scale  % in.=l  in. 


either  to  the  right  or  to  the  left  without  disturbing  the  joint  and  causing 
it  to  leak.  For  this  reason  these  pipes  are  connected  with  what  are  called 
ball-joints , fig.  210 — that  is,  the  end,  a b,  of  one  of  the  pipes  is  turned  into 


Fig.  210.  Steam-Pipe  Joint.  Scale  % in.=l  in. 


the  form  of  a part  of  a sphere,*  and  the  end  of  the  other  one  into  a corres- 
ponding concave  form.  It  is  known  that  a sphere  will  fit  into  a spherical 
socket  in  any  position  ; for  example,  an  acorn  in  its  cup  or  the  bones  at 

* The  dotted  lines  indicate  what  would  be  the  form  of  the  sphere  if  the  pipe  was  solid  instead 
of  hollow. 


258 


Catechism  of  the  Locomotive. 


the  hip  or  shoulder  joints.  If,  therefore,  the  pipes  are  joined  with  such 
spherical  or  ball-joints,  as  they  are  called,  the  lower  end  can  be  moved 
sideways  several  inches  either  way,  and  the  joint  will  still  be  steam  tight 
if  it  is  then  firmly  bolted  together.  Even  after  it  is  bolted  together  it  will 
have  so  much  flexibility  that  the  expansion  and  contraction  of  the  pipes 
will  not  cause  it  to  leak. 

There  is,  however,  still  another  difficulty.  Although  the  lower  end  of 
the  pipe,  84,  fig.  98,  can,  with  a ball-joint  above,  be  moved  in  any  direc- 
tion horizontally,  yet  if  the  pipe  is  too  long  or  too  short  it  is  obvious  such 
a joint  will  not  permit  it  to  be  moved  up  or  down.  A joint  with  a flat 
surface,  like  that  shown  in  fig.  209,  would,  however,  permit  such  motion 
in  the  pipe  without  leaking.  If,  for  example,  the  steam-pipe  were  inch 
too  short,  it  might  be  drawn  down  that  distance,  and  if  the  upper  joint 
were  then  screwed  up  it  would  still  be  steam-tight.  In  order,  then,  to  get 
both  vertical  and  lateral  flexibility  in  the  joints  of  the  steam-pipes,  a ring, 
a b,  fig.  211,  is  interposed  between  the  pipes.  One  side  of  this  ring  is 


Fig.  211.  Steam-Pipe  Joint.  Scale  % in.=l  in. 


spherical  and  the  other  flat,  so  that  the  pipes  can  move  either  around  the 
spherical  part  or  slip  up  or  down  or  sideways  on  the  flat  surface  of  the 
ring.  In  this  way  the  pipes  are  flexible  and  adjustable  in  every  direction, 
and  for  all  kinds  of  motion  caused  by  expansion,  or  which  may  be  needed 
when  the  parts  are  put  together.  Sometimes  the  joints  at  one  end  only 
of  the  steam-pipes  are  made  in  this  way,  and  the  other  is  connected  with 
a simple  ball-joint. 

In  designing  these  joints  their  form  should  be  drawn  with  a radius,  c d, 
fig.  210,  from  one  centre,  c , so  that  the  surface  of  the  joint  will  form  a part 


The  Throttle-Valve  and  Steam-Pipes. 


259 


Fig.  212. 


a 


Fig.  213. 


Scale  1 in.=l  ft. 


260 


Catechism  of  the  Locomotive. 


of  a sphere.  If  they  are  drawn  from  two  centres,  as  is  sometimes  done,  it 
is  obvious  that  the  surface  of  the  joint  will  not  be  a part  of  a sphere,  and 
therefore  will  not  have  the  requisite  flexibility.  The  surfaces  of  the  joints 
are  carefully  turned  to  the  proper  form,  and  then  made  steam-tight  by 
scraping  or  grinding  them  with  emery  and  oil,  and  the  pipes  are  then  fas- 
tened together  with  bolts,  g g,  fig,  211,  and  flanges,  f f,  cast  on  the  pipes. 

Question  326.  How  are  the  exhaust-pipes  made? 

Answer.  They  are  made  of  cast  iron.  Two  forms  of  such  pipes  are 
shown  by  figs.  212  to  217.  These  figures  show  vertical  sections,  plans, 
and  inverted  plans  of  the  pipes.  In  some  cases  a single  blast  orifice  or 
exhaust-nozzle  is  used,  as  shown  in  figs.  212  and  213,  and  in  others  they 
are  made  double,  as  they  are  represented  in  figs.  215  and  216.  Where 
two  nozzles  are  used  they  are  generally  cast  together,  as  shown  in  figs. 
215-217.  When  only  one  is  used,  the  form  of  the  pipes  resembles  some- 
what that  of  an  inverted  letter  as  shown  in  fig.  213,  so  as  to  cover  the 
two  openings  which  connect  with  the  cylinders.  The  tops  of  these  pipes 
have  rings  or  bushings,  a a,  fitted  into  them,  which  are  held  by  set  screws, 
b b,  so  that  they  can  easily  be  removed  and  others  with  larger  or  smaller 
openings  be  substituted.  If  the  openings  in  the  exhaust-nozzles  are  small, 
the  steam  must  be  discharged  at  a higher  rate  of  speed,  in  order  to  ex- 
haust that  which  is  in  the  cylinders,  than  if  the  blast  orifices  are  larger. 
Therefore,  if  the  latter  are  reduced  in  size,  the  draft  becomes  more  violent, 
but  at  the  same  time  the  back-pressure  in  the  cylinder  (which  will  be  ex- 
plained hereafter)  is  increased.  It  therefore  becomes  necessary  to  adjust 
the  size  of  the  blast  orifices  with  the  greatest  care,  so  as  to  have  them  just 
small  enough  to  produce  the  required  draft  and  yet  leave  them  as  large 
as  possible,  so  as  to  reduce  the  back-pressure.  For  these  reasons  what 
are  called  variable  exhausts  are  sometimes  used.  In  these  the  blast  orifice 
can  be  increased  or  diminished  at  pleasure,  and  thus  regulated  to  suit  the 
conditions  under  which  an  engine  is  working.  A great  variety  of  such 
devices  has  been  used,  but  now  nearly  all  have  been  abandoned  for  the 
simpler  arrangement  described,  which  is  not  variable  when  the  engine  is 
working. 

Figs.  218  and  219  represent  longitudinal  and  transverse  sections  of 
Adams’ “ vortex  blast-pipe,”  which  is  the  invention  of  Mr.  W.  Adams, 
locomotive  superintendent  of  the  London  & South  Western  Railway.* 
The  main  object  of  this  invention  is  to  equalize  the  draft  through  the 
tubes  of  the  locomotive  and  thus  to  prevent  the  destructive  action  of  the 


* This  has  been  patented  in  this  country  and  in  England. 


The  Throttle-Valve  and  Steam-Pipes. 


261 


blast,  which,  with  ordinary  blast-pipes,  act  with  too  great  intensity  through 
the  upper  rows  of  tubes.  To  overcome  this,  Mr.  Adams  makes  the  ex- 
haust orifice,  A A,  of  annular  form,  as  shown  clearly  in  the  plan  below,  fig. 
219.  The  lower  part  of  the  exhaust-pipe  is  made  of  a bifurcated  form, 


somewhat  like  a pair  of  trousers,  the  two  legs  or  branches,  B B,  being 
attached  to  the  exhaust  pipes,  E E.  The  branches,  B B,  have  an  open- 
ing, F,  between  them,  and  unite  in  the  annular  opening,  C C,  above  the 
partitions,  D D,  shown  by  dotted  lines  in  fig.  219,  and  black  shading  in 


262  Catechism  of  the  Locomotive. 

fig.  218.  Inside  of  the  annular  nozzle,  A A,  there  is  a cylindrical  central 
passage,  G,  which  communicates  directly  with  the  opening,  F.  When 
steam  escapes  from  the  opening,  A A,  it  draws  the  air  with  it  on  the  out- 
side of  the  exhaust  pipe,  P P,  and  of  the  escaping  current  of  steam.  It 
also  creates  a partial  vacuum  in  the  central  passage,  G,  which  draws  air 
from  the  opening,  F , and  from  the  lower  part  of  the  smoke-box  and  lower 
rows  of  tubes.  In  this  way  the  draft  in  the  upper  and  lower  tubes  is 
equalized  which,  it  is  said,  results  in  a material  economy  in  fuel  consump- 
tion. 


CHAPTER  XV. 


THE  CYLINDERS,  PISTONS,  GUIDE-BARS,  CROSS-HEADS  AND  CONNECTING- 

RODS. 

Question  327.  How  are  the  steam  cylinders  constructed? 

Answer.  They  are  made  of  hard  cast  iron,  and  have  the  steam  and 
exhaust-ports  and  valve-seats  cast  with  them.  The  harder  the  iron  the 
better  will  the  cylinders  withstand  the  wear  of  the  pistons  and  valves,  but 
they  must  at  the  same  time  be  made  soft  enough,  so  that  after  they  are 
cast  the  inside  can  be  bored  out  perfectly  cylindrical,  the  ends  turned  off, 
the  bolt-holes  drilled,  and  the  valve-seats  planed  smooth. 

Fig.  220  represents  a longitudinal  section  through  the  centre  of  the 
cylinder  and  steam-chest.  Fig.  221  is  a plan  of  the  same  parts  with  the 
cover  of  the  steam-chest  and  the  valve  removed.  Fig.  222  is  a front  end 
view,  and  fig.  223  a transverse  section,  through  c d , fig.  221,  of  the  cylin- 
der. Fig.  224  is  a transverse  section  through  the  guide-bars,  N N,  fig. 
221,  looking  backward  towards  the  cross-head  and  cylinder.  The  same 
letters  indicate  like  parts  in  the  different  views. 

The  cylinders  of  locomotives  in  this  country  are  now  universally  placed 
on  the  outside  of  the  wheels,  as  has  already  been  described.  In  order  to 
fasten  them  securely  together  and  to  the  boiler,  they  are  attached  to  what 
is  called  bed-plates  or  bed-castings , D D,  figs.  222  and  223,  which  are  placed 
between  them.  Sometimes  the  bed-castings  are  made  separate  from  the 
cylinders  and  in  one  piece,  and  the  cylinders  are  then  bolted  to  it  on  the 
outside,  about  at  the  dotted  lines,  / m,  fig.  222.  The  usual  practice  now 
is  to  cast  one-half  of  the  bed-casting  with  each  cylinder,  as  shown  in  the 
engravings,  and  then  bolt  them  together  at  the  line,  / i,  which  is  the 
centre  of  the  engine.  The  bed-castings  are  also  bolted  to  the  smoke-box 
by  the  flanges,  is  is.  The  cylinders  are  bolted  to  the  frames,  F F,  with 
bolts,  m and  k , figs.  222  and  223. 

After  the  cylinders  are  bored  out  and  the  ends  turned  off,  heads , A and 
B,  fig.  220,  are  fitted  with  steam-tight  joints  to  each  end.  These  heads 
are  fastened  with  bolts  and  nuts,  a a a,  to  flanges,  C C,  fig.  221. 

QUESTION  328.  How  is  the  steam  co7iducted  to  and  from  the  cylinder? 


Fig.  220.  Longitudinal  Section  of  Cylinder,  etc.  Scale  % in.=l  in. 


Fig.  221.  Plan  of  Cylinder,  etc.  Scale  % in.«=l  in. 


Fig.  223.  Transverse  Section  of  Cylinder. 


Cylinders,  Pistons,  Guide-Bars,  Cross-Heads,  etc. 


26' 


Answer.  Two  pipes  or  passages  are  cast  in  each  cylinder,  the  one,  G, 
fig.  223,  for  admitting  steam  into  the  steam-chest,  and  the  other,  H H' , 
the  exhaust-passage.  The  steam-passage  terminates  at  one  end  with  a 
round  opening,  G,  figs.  221  and  223,  to  which  the  steam-pipe,  84  84',  fig. 
98,  are  attached  inside  of  the  smoke-box.  At  the  other  end  it  divides 
into  two  branches,  G'  G' , shown  by  dotted  lines  in  fig.  221,  each  of  which 
terminates  in  an  opening,  g g',  inside  of  the  steam-chest.  The  steam  is 
thus  delivered  at  both  ends  of  the  chest,  and  can  pass  freely  into  each  of 
the  steam-ports,/*  f,  when  they  are  open.  By  making  the  cylinders  in 
this  way,  they  are  exactly  alike  for  each  side  of  the  engine,  or,  to  use  a 
shop  phrase,  there  are  “ no  rights  and  lefts,”  so  that  a cylinder  casting  can 
be  used  for  either  side  of  the  engine.  This  method  of  making  cylinders 
has  been  adopted  by  nearly  all  the  principal  builders  in  this  country. 


Fig.  224. 


Back-end  View  of  Cylinder  and  Cross-Head.  Scale  % in.=l  in. 


QUESTION  329.  How  are  the  steam-chests  constructed  ? 

Answer.  They  usually  consist  of  two  castings,  one  of  which,  J J,  figs. 
220,  221,  222  and  223,  is  a square  cast-iron  box  made  open  at  the  top  and 
bottom.  This  rests  on  the  top  of  the  cylinder  casting  and  is  joined  to 
the  latter  with  a steam-tight  joint.  On  top  of  it  is  a cast-iron  cover,  K. 
The  steam-chest  and  cover  are  held  down  by  bolts,  p p,  which  are  screwed 
into  the  cylinder  casting  and  have  nuts  on  top. 

QUESTION  330.  How  are  the  slide-valves  made  to  work  steam-tight  on 
the  valve-seats  ? 

Answer.  They  are  first  planed  off  smooth,  and  then  filed  and  scraped 
until  the  two  touch  each  other  over  the  whole  of  their  surfaces  in  contact. 
The  valve-stem,  v,  fig.  220,  works  steam-tight  through  a stuffing-box,  s, 
on  the  steam-chest. 


268 


Catechism  of  the  Locomotive. 


QUESTION  331.  Haw  are  the  valves  and  pistons  oiled? 

Answer.  The  oil  is  usually  introduced  into  the  steam-chest  through  a 
pipe,  c,  which  is  connected  with  a cock  in  the  cab,  called  the  cylinder  oil- 
cock  or  “oiler!'  From  this  cock  the  oil  flows  through  the  pipe  and  down 
upon  the  valve,  and  is  conducted  by  suitable  holes  and  channels  to  the 
valve-face,  and  from  there  through  the  steam-ports  to  the  cylinder  and 
piston.  The  construction  of  these  “oilers  ” is  explained  in  Chapter  XXI. 

Sometimes  the  valves  are  oiled  by  pouring  oil  or  melted  tallow  into  the 
oil-cocks  when  the  steam  is  shut  off  from  the  steam-chests  and  cylinders. 
When  the  pistons  are  working  in  the  cylinders  without  steam,  they  create 
a partial  vacuum,  so  that  if  oil  is  then  poured  into  the  oil-cocks  it  will  be 
sucked  into  the  steam-chests,  or,  in  other  words,  it  will  be  forced  in  by 
the  pressure  of  the  air  above  it.  A shelf,  105,  fig.  99,  is  attached  to  the 
boiler  to  receive  an  oil-can  filled  with  oil  or  tallow,  which  is  thus  melted 
or  kept  in  a fluid  condition  by  the  heat  of  the  boiler. 

Question  332.  How  are  the  cylinders  and  steam-chests  protected  so  as 
to  prevent,  as  far  as  possible , the  heat  in  the  steam  from  being  lost  ? 

Answer.  The  sides  of  the  cylinders  are  covered  with  wood,  shown  at  w 
w w,  figs.  220  and  223,  called  the  cylinder -l agg ing , and  the  wood  is  covered 
outside  with  Russia  iron,  which  is  called  the  cylinder -casing.  The  ends 
of  the  cylinders  have  light  metal  covers,  called  cylinder-head  covers,  shown 
in  section  at  a a,  fig.  220,  made  of  cast-iron,  brass,  or  sheet  metal,  The 
steam-chest  has  a similar  cover,  2 2,  fig.  220.  Sometimes  coarse  felt  is 
used  for  lagging  the  cylinder  and  steam-chest. 

Question  333.  For  what  purpose  are  the  cocks,  L L,figs.  220,  222  and 
223,  at  each  end  of  the  cylinder,  used? 

Answer,  They  are  used  to  exhaust  the  water  which  collects  in  the  cyl- 
inders. When  the  engine  is  not  working  the  cylinders  and  steam-pipes 
are  all  cooled  off,  so  that  when  steam  is  first  introduced  into  them  a great 
deal  of  it  is  condensed  until  they  become  warmed.  Water  is  also  fre- 
quently carried  over  from  the  boiler  with  the  steam.  When  this  occurs 
the  boiler  is  said  to  prime,  or  to  “ work  water."  This  water  and  that  pro- 
duced by  the  condensation  of  steam,  collects  in  the  bottoms  of  the  cylinders 
and  will  not  escape  through  the  exhaust-pipes  until  the  piston  moves  up 
so  near  to  the  end  of  the  cylinder  that  the  water  will  fill  the  whole  space 
between  it  and  the  cylinder-head.  As  has  already  been  stated,  it  will 
then  escape  so  slowly  that  the  momentum  of  the  piston  and  other  machin- 
ery is  liable  to  “knock  out  ’ the  cylinder-heads  or  even  break  the  cylinder 
itself.  The  cocks,  L L,  called  cylinder-cocks,  are  therefore  placed  in  the 


Cylinders,  Pistons,  Guide-Bars,  Cross-Heads,  etc.*  269 

under  side  of  the  cylinder,  so  that  when  they  are  open  if  there  is  any 
water  in  the  cylinder  it  will  escape  through  them.  They  are  therefore 
always  opened  when  the  engine  is  starting,  or  at  any  other  time  when 
there  is  any  indication  that  there  is  water  in  the  cylinders. 

Question  334.  How  are  these  cocks  opened  or  closed? 

Answer.  A shaft,  R,  fig.  220,  which  extends  across  the  frames,  has  an 
arm,  R S,  at  each  end.  These  arms  are  connected  by  rods,  S T,  with  the 
handles  of  the  cylinder-cocks.  The  shaft  also  has  a verticle  arm,  R V , 


the  upper  end  of  which  is  connected  by  a rod  with  the  cab.  At  the  end 
of  the  rod  is  a suitable  handle  by  which  the  cocks  can  be  either  opened  or 
closed  at  pleasure  by  the  locomotive  engineer. 

Question  335.  How  is  the  piston-rod  fastened  to  the  piston? 

Answer.  It  fits  into  a straight  or  tapered  hole  in  the  piston-head,  in 
which  it  is  fastened  either  with  a key  or  by  a nut  on  the  front  side  of  the 
piston. 

Question  336.  How  are  pistons  constructed? 

Answer.  They  are  made  in  a variety  of  ways.  Figs.  225  and  226  re- 
present a form  of  piston  which  has  been  used  for  many  years  and  is  still 


270 


Catechism  of  the  Locomotive. 


preferred  by  some  engineers.  Fig.  225  shows  the  front  side  of  the  piston 
with  one-half  of  the  follower-plate  removed,  and  fig.  226  is  a longitudinal 
section. 

They  are  made  of  two  cast-iron  pieces,  B and  C,  fig.  226,  the  one,  B, 
called  the  piston-head  or  spider , to  which  the  piston-rod,  D,  is  attached. 
The  other  part,  C,  called  the  follower-plate , is  bolted  to  the  piston-head  by 
the  bolts,/ /,  called  follower-bolts . 

Question  337.  How  are  pistons  made  to  work  steam-tight  in  the 
cylinder  ? 

Answer.  The  old  way  of  making  pistons  is  shown,  as  noted  above,  in 
figs.  225  and  226.  Pistons  of  this  kind  have  two  rings,  A A,  called  pack- 
ing-rings. These  rings  are  turned  of  the  same  size  or  a little  larger  in  di- 
ameter than  the  cylinder.  They  are  then  cut  open  at  one  point  in  their 
circumference  so  that  they  can  be  pressed  apart  or  expanded  by  the 
springs,  a a,  called  packing-springs , on  the  inside  of  the  rings.  These 
springs  are  pressed  out  by  the  nuts  and  bolts,  b b,  called  packing-bolts  and 
packing-nuts , so  that  when  the  rings  wear  they  can  be  expanded  so  as  to 
fill  the  cylinder  completely.  The  place  where  the  one  ring  is  cut  is  placed 
on  the  opposite  side  of  the  piston  from  that  of  the  opening  in  the  other  ring, 
or  they  are  made  to  break  joints,  as  it  is  called.  This  is  done  to  prevent 
the  steam  which  leaks  through  the  opening  where  the  one  ring  is  cut  from 
passing  through  to  the  other  side  of  the  piston.  These  rings  are  usually 
made  of  brass  and  have  groves,  c c,  fig.  226,  turned  in  them,  which  are 
filled  with  what  is  called  Babbitt’s  metal.  This  metal  is  used  because  it 
is  less  liable  to  scratch  the  cylinders  than  brass.  Another  ring,  / /, 
made  of  cast-iron  and  as  wide  as  the  two  brass  rings,  is  placed  inside  of 
the  latter  and  is  intended  to  furnish  a bearing  for  the  springs,  and  thus 
distribute  their  pressure  equally  on  the  packing  rings.  This  iron  ring  is 
also  cut  open  at  one  point.  The  follower-bolts,/ f,  are  screwed  into  brass 
nuts,  N N,  which  are  contained  in  cavities  cast  in  the  lugs,  L L , on  the 
piston-head.  These  brass  nuts  are  used  to  prevent  the  bolts  from  rusting 
fast,  as  they  are  liable  to  when  screwed  into  the  cast-iron  of  which  the 
piston-head  is  made. 

Question  338.  What  other  kinds  of  pistons  are  there? 

A?iswer.  A number  of  different  kinds  are  used  with  packing-rings  of 
various  forms  which  are  usually  made  larger  in  diameter  than  the  inside 
of  the  cylinders.  After  being  cut  apart  they  are  compressed  so  as  to  enter 
the  cylinders,  and  their  own  elasticity  or  tendency  to  spring  apart  keeps 
them  tight.  Figs.  227,  228  and  229  represent  one  form  of  this  kind  of 


Cylinders,  Pistons,  Guide-Bars,  Cross-Heads,  etc. 


271 


packing.  It  consists  of  a main  ring,  / /,  which  has  two  grooves  turned  in 
it  which  receives  the  two  rings,  A A ; these,  as  explained,  are  made  some- 
what larger  than  the  cylinder.  They  are  cut  apart  and  are  held  in  the 
grooves  by  a flange  on  the  piston-head  on  one  side,  and  by  the  follower- 
plate  on  the  other.  The  ring,  l /,  is  not  cut  open,  but  is  left  solid,  and  the 
weight  of  the  piston  causes  this  ring  to  bear  on  the  bottom  of.  the  cylin- 


Fig.  227. 


Fig.  228. 

A l A 


A l A 


Fig.  229. 

Piston  with  Steam  Packing.  Scale  % in.=l  in. 


der.  The  openings,  b b,  where  the  ring,  A A,  are  cut  apart,  are  placed  at 
the  bottom  of  the  piston,  as  shown  in  figs.  227  and  228.  Fig.  229  is  an  in- 
verted plan  of  the  piston,  and  shows  the  position  of  the  openings.  As 
the  ring,  /,  bears  on  the  bottom  of  the  cylinder  it  keeps  the  piston  tight 
at  that  point,  so  that  any  steam  which  may  leak  through  either  of  the 
openings,  b b,  could  get  no  further  than  the  ring,  /.  The  elasticity  of  the 


272 


Catechism  of  the  Locomotive. 


rings,  A A,  cause  them  to  bear  against  the  top  and  sides  of  the  cylinder 
and  in  that  way  keep  them  tight ; a a are  pins  to  prevent  the  rings,  A A, 
from  turning. 

In  some  other  pistons  the  packing-rings  are  cut  into  sections  and  are 
either  pressed  out  by  some  form  of  springs,  or  steam  is  admitted  to  the 
grooves  in  which  they  are  held  so  as  to  press  them  out  against  the  inner 
surface  of  the  cylinder,  and  thus  keep  the  piston  tight. 

Question  339.  How  is  the  piston-rod  made  to  work  steam-tight  through 
the  cylinder-head  ? 

Answer.  By  what  is  called  a stuffing-box,  similar  to  that  illustrated  in 
figs.  44  and  45,  and  described  in  the  answer  to  Question  95.  Such  a stuffing- 
box  is  shown  at  r,  fig.  220  and  on  a larger  scale  in  figs.  230  and  231.  Fig. 
230  is  a longitudinal  section,  and  fig.  231  a front  view  of  such  a stuffing- 
box. 


Question  340.  How  is  metal  packing  for  piston-rods  and  valve-stems 
made  ? 

Answer.  A number  of  different  kinds  of  metal  packing  are  now  used. 
One  of  these  kinds,  made  by  the  United  States  Metallic  Packing  Com- 
pany, of  Philadelphia,  is  illustrated  by  fig.  232.  It  consists  of  a cap,  1 1, 
which  is  bolted  over  the  stuffing-box.  The  latter  contains  a number  of 
metal  rings,  in  which  the  piston-rod,  B,  works.  These  rings  are  made  as 
follows  : 3 3 is  a solid  ring  made  of  brass,  with  a spherical  surface  on  one 
side,  which  bears  against  the  cap,  1 1,  and  has  a flat  surface  on  the  other 


Cylinders,  Pistons,  Guide-Bars,  Cross-Heads,  etc.  273 

side.  A solid  cast-iron  ring,  4 4,  bears  against  the  flat  surface  of  3 3 ; 4 4 
has  a conical  cavity  on  the  inside  which  contains  a number*of  soft  metal 
rings,  5 6 6,  which  are  cut  into  a number  of  pieces  or  sectors.  A solid 
brass  ring,  7 7,  bears  on  these,  and  is  pressed  against  them  by  a spiral 
spring,  8.  The  steam  in  the  cylinder  also  presses  on  these  rings  and 
forces  the  soft  metal  packing  rings  into  the  conical  cavity  in  ring  4,  which 
causes  them  to  contract  and  bear  against  the  piston-rod,  and  thus  make 
them  steam-tight.  The  spiral  spring  holds  the  rings  in  place  on  the  return 


Fig.  232.  Metallic  Piston-Rod  Packing.  Scale  % in.=l  in. 

stroke  of  the  piston,  when  the  steam  in  the  back  end  of  the  cylinder  is 
exhausted  or  when  steam  is  shut  off  from  the  cylinders.  The  purpose  of 
the  spherical  and  flat  surfaces  of  the  ring,  3,  is  to  permit  it  to  adjust  itself 
to  any  position  of  the  piston-rod  in  case  it  should  “ get  out  of  line,”  some- 
what as  steam-pipes  are  kept  tight  by  a similar  method  of  construction, 
as  explained  in  Chapter  XIV. 

Question  341.  Why  is  the  end  of  the  piston-rod  made  to  work  in 
guides  ? 

Answer.  Because,  as  was  explained  in  answer  to  Questions  96,  97  and 
98,  it  must  move  in  a straight  line  if  it  and  the  piston  work  steam-tight 
in  the  cylinder.  By  referring  to  fig.  A,  Plate  I,  it  is  obvious  that  if  a 
pressure  be  exerted  against  the  piston,  B,  and  communicated  to  the  crank- 
pin,  N,  by  the  connecting-rod,  E,  the  latter,  excepting  at  the  dead-points, 
will  exert  a pressure  either  upward  or  downward,  according  to  the  direc- 
tion the  piston  is  moving.  This  pressure  would  bend  the  piston-rod  if 


274 


Catechism  of  the  Locomotive. 


no  provision  were  made  to  prevent  it.  For  this  reason  the  end  of  the 
piston-rod  is  attached  to  what  is  called  a cross-head , M,  figs.  220,  221  and 
224,  which  works  in  guides,  N N,  N'  N\  called  guide-bars  or  guides. 

Question  342.  What  are  the  different  forms  of  cross-heads  and  guides 
that  are  used ? 

Answer.  The  cross-head  shown  in  the  figures  .last  referred  to  is  the  one 
that  is  generally  used  on  passenger  engines.  The  cross-head  is  made  of 
cast  iron  or  cast  steel,  and  has  slides,  m m , fig.  224,  one  on  each  side,  which 
work  between  pairs  of  guide-bars,  NN\  shown  in  section  in  fig.  224.  These 


guide-bars  are  planed  and  finished  with  great  accuracy,  so  as  to  be  straight 
and  smooth,  and  are  attached  to  the  back  cylinder-head  and  to  a support, 
O,  fig.  220,  called  the  guide-yoke,  which  is  a plate  fastened  to  the  frame  at 
F,  fig.  221,  and  is  also  usually  attached  to  the  boiler.  The  guides  are  set 


Cylinders,  Pistons,  Guide-Bars,  Cross-Heads,  etc. 


275 


with  great  care,  so  as  to  be  exactly  parallel  with  the  axis  or  centre  line  of 
the  cylinder,  so  that  the  cross-head  will  slide  in  exactly  the  same  path  that 
the  piston-rod  will  if  it  moves  in  a straight  line.  If,  then,  the  piston-rod 
and  the  connecting-rod  are  attached  to  the  cross-head  all  the  strain  pro- 
duced by  the  obliquity  of  the  connecting-rod  will  be  borne  by  the  guides, 
thus  relieving  the  piston-rod,  and  making  it  certain  that  it  will  move  in  a 
straight  line. 

Figs.  23B  and  234  represent  cross-heads  which  are  used  on  freight  en- 
gines. In  fig.  233  there  is  a single  guide-bar,  A,  above,  and  another,  B, 
below  the  cross-head.  In  fig.  234  there  is  a single  guide-bar,  A,  above  the 
cross-head ; sometimes  two  bars  above  the  cross-head  are  used  instead  of 
the  single  bar.  These  forms  are  used  when  one  of  the  driving-wheels  is 
opposite  to  the  guide-bars,  as  is  the  case  on  mogul,  consolidation,  and 
some  other  engines.  In  such  cases  there  is  not  room  enough  to  place  the 
guide-bars  on  each  side  of  the  cross-head. 

Question  343.  How  are  the  piston  and  connecting-rods  attached  to  the 
cross-head  ? 

Answer.  The  end  of  the  piston-rod  fits  into  a tapered  hole  in  the  cross- 
head, and  is  held  by  a key,  w,  figs.  220  and  221,  and  k k , figs.  233  and  234. 
The  connecting-rod  is  attached  to  a pin,  Q,  figs.  220  and  221,  called  a 
wrist-pin , which  is  cast  with  the  cross-head. 

QUESTION  344.  How  is  the  wear  of  the  slides  lessened  and  compensated 
for ? 

Answer.  Sometimes  they  are  made  with  brass  wearing  pieces  called 
gibs , shown  above  and  below,  m m,  fig.  224,  which  are  placed  between  the 
slides  and  the  guides.  These  gibs  can  either  be  removed  and  new  ones 
substituted  when  they  become  very  much  worn,  or  by  inserting  thin  pieces 
of  metal,  called  liners,  between  them  and  the  cross-head,  they  will  be 
spread  apart  so  as  to  fill  the  space  between  the  slides.  The  slides  are 
now,  however,  often  made  without  gibs,  and  have  recesses  either  cast  or 
drilled  in  them,  which  are  filled  with  Babbitt’s  metal.  Double  guide-bars 
are  bolted  at  each  end  to  blocks,  x x,  fig.  220,  called  guide-blocks,  which 
can  be  planed  off  so  as  to  bring  the  guides  nearer  together  when  they  and 
the  slides  are  worn.  Sometimes  liners  are  placed  between  the  blocks  and 
the  guides,  which  can  be  removed  when  it  is  necessary  to  bring  the  guides 
nearer  together. 

Question  345.  Are  the  guides  worn  alike? 

Answer.  No ; as  explained  in  the  answer  to  Question  154,  when  an 
engine  is  running  forward  the  connecting-rod  presses  the  cross-head 


276 


Catechism  of  the  Locomotive. 


upward  during  both  the  forward  and  the  backward  stroke  of  the  piston, 
and  in  running  backward  the  pressure  of  the  rod  is  downward. 

This  will  be  understood  by  referring  back  to  the  series  of  figures  from 
30  to  43.  It  will  be  noticed  that  in  the  backward  stroke  of  the  piston, 
represented  by  figs.  30  to  36,  the  strain  on  the  connecting-rod  tends  to 
push  the  cross-head  upward,  and  in  the  forward  part  of  the  stroke,  figs. 
37  to  43,  the  connecting-rod  pulls  the  cross-head  in  the  same  direction. 
If  the  crank  turned  the  opposite  way,  this  action  would  be  reversed  and 
the  cross-head  would  then  be  alternately  pushed  and  pulled  downward. 
Consequently,  when  the  engine  is  running  forward  the  surfaces  of  the 
guide-bars,  which  resist  the  upward  pressure  of  the  cross-head  will  be 
worn  most,  and  in  running  backward,  those  which  resist  its  downward 
pressure  will  be  worn  most.  As  nearly  all  locomotives  run  forward  more 
than  backward,  the  under  surfaces  are  usually  worn  the  most. 

Question  346.  How  are  the  slides  oiled? 

Answer.  Oil  cups,  3 3,  are  attached  either  to  the  top  guides,  as  shown 
in  figs.  220,  221  and  222,  or  to  the  cross-head,  as  indicated  by  o,  in  fig.  234. 
These  cups  usually  have  a reservoir  to  hold  a supply  of  oil,  and  are  so  con- 
structed that  it  will  be  gradually  fed  on  the  slides,  which  are  thus  con- 
stantly and  regularly  lubricated.  Their  construction  is  explained  in 
Chapter  XXI. 

Question  347.  How  are  the  pumps  worked  by  the  piston? 

Answer.  The  pump-plunger,  4,  figs.  221  and  224,  is  attached  to  a pro- 
jection, W,  called  the  pump-lug,  cast  on  one  of  the  slides  of  the  cross- 
head. The  plunger  thus  receives  a reciprocating  motion  from  the  piston. 

Question  348.  What  are  the  connecting-rods  for? 

Answer.  The  rods  which  connect  the  cross-heads  to  the  main  crank- 
pins — which  are  called  main  connecting-rods — commuuicate  the  pressure 
on  the  piston  to  the  main  crank-pin.  The  rods  which  connect  or  couple 
the  crank-pins  on  adjoining  driving-wheels  together  are  called  coupling- 
rods,*  and  they  cause  the  wheels  to  revolve  together. 

Question  349.  To  what  strains  are  the  connecting-rods  subjected? 

Answer.  They  are  alternately  subjected  to  a strain  of  tension  and  com- 
pression by  the  pressure  of  the  steam  on  the  pistons  during  their  forward 
and  backward  strokes.  They  must  also  resist  the  centrifugal  force  due  to 
their  revolution,  which  produces  a bending  action  on  the  rods. 

Question  350.  How  are  the  connecting-rods  made? 

* They  are  also  often  called  side  or  parallel-rods , but  the  term  coupling-rods  is  considered  the 
best, 


Cylinders,  Pistons,  Guide-Bars,  Cross-Heads,  etc. 


277 


Answer.  They  are  made  of  flat  bars  of  wrought  iron.  Figs.  235  and 
236  represent  a side  view  and  a plan  of  a main  connecting-rod.  It  is 
attached  to  the  wrist-pin  of  the  cross-head  at  A , and  to  the  crank-pin  at 
B.  Figs.  237  and  238  represent  similar  views  of  a coupling-rod.  To  save 
room  in  the  engraving  each  of  these  rods  is  represented  with  a part  of  the 
middle  broken  away,  and  a transverse  section  of  the  middle  of  the  rod  is 
shown  at  T and  T,  between  the  broken  ends.  The  main  rods  are  usually 
made  wider  at  G,  next  the  crank-pin,  than  at  the  other  end,  as  it  has  been 
found  that  they  are  most  liable  to  break  next  to  the  “big  end,”  B,  as  it  is 
called,  than  at  any  other  place.  The  coupling-rods  are  now  made  either 
straight  or  somewhat  wider  in  the  centre.  To  give  them  greater  strength 
without  increasing  their  weight  too  much,  the  sections  of  such  rods  are 
often  made  “fluted”  as  it  is  called — that  is,  with  a section  of  the  form  of 
the  letter  I. 

Question  351.  How  are  these  rods  prevented  frotn  getting  loose  on  the 
pins  from  the  wear  of  the  latter  in  the  inside  of  the  holes  of  the  rods  ? 

Answer.  By  a stub-end  or  strap-end  similar  to  that  described  in  answer 
to  Question  99.  The  ends  of  the  rods  are  provided  with  what  are  called 
brass  bearings , or  “ brasses c d and  e f,  figs.  235  and  236.  These  brasses 
are  made  in  pairs,  so  as  to  embrace  the  pins  from  each  side.  They  are 
held  by  U-shaped  clamps,  s s s,  called  straps , which  are  bolted  to  the  rods. 
When  the  brass  bearings  become  worn,  they  are  taken  out  of  the  straps, 
and  a portion  of  their  surfaces  of  contact  with  each  other  is  filed  away, 
thus  allowing  them  to  come  nearer  together,  and  thereby  reducing  the 
size  of  the  hole  which  receives  the  pin  or  journal.  In  order  to  prevent 
their  being  loose  in  the  straps,  tapered  or  wedge-shaped  keys,  k k , are 
fitted  in  the  straps  and  rods.  By  driving  down  these  keys,  the  straps  are 
drawn  against  the  brass  bearings  and  they  are  forced  together,  thus 
reducing  the  size  of  the  hole  for  the  journal,  and  making  the  rods  fit 
tightly  on  the  pins.  A hard  steel  plate,  p,  fig.  235,  is  sometimes  inter- 
posed between  the  keys  and  the  brasses  to  prevent  the  key  from  indenting 
the  surface  of  the  soft  brass.  As  the  keys  are  very  liable  to  get  loose  and 
fall  out,  they  are  held  either  by  screws  and  nuts,  x x,  as  shown  on  the 
left-hand  side  of  the  engraving,  or,  as  shown  at  the  other  end  of  the  rod, 
by  a set-screw , r,  on  the  other  side  of  the  rod.  The  ends  of  coupling-rods 
sometimes  have  stub-ends,  as  shown  in  figs.  237  and  238,  but  are  often 
made  without,  and  with  simple  bushings  or  brass-rings,  b b,  driven  into 
holes  in  the  ends,  as  shown  in  fig.  239.  When  these  bushings  become 
worn  they  are  taken  out  and  new  ones  are  put  in  their  places. 


O' 

o 

T 


u 


^ 

© 

© 


o 


Fig.  238.  Coupling-Rod.  Scale  1 in.=l  ft. 


280 


Catechism  of  the  Locomotive. 


Question  852.  How  are  the  journals  of  the  crank-pins  oiled? 

Answer.  By  oil-cups,  o o,  figs.  235-240,  attached  to  the  straps  above 
the  journals,  similar  to  the  cups  used  on  the  guide-rods.  Sometimes  oil- 
cellars,  as  they  are  called,  are  attached  to  the  under  side  of  the  straps. 
These  are  metal  boxes,  which  are  filled  with  oil,  which  is  agitated  violently 
by  the  rapid  motion  of  the  rods,  and  is  thus  applied  to  the  journals 
through  holes  drilled  in  the  straps.  In  order  to  confine  the  oil  and  pre- 
vent its  leaking  out  around  the  journals  of  the  coupling-rods,  the  brasses 
are  sometimes  made  so  as  to  enclose  the  outside  end  of  the  crank-pin, 
which  thus  not  only  keeps  the  oil  in,  but  excludes  the  dust.  The  brasses 
are  usually  lined  with  Babbitt’s  or  some  other  kind  of  soft  metal,  which 
is  thought  to  be  less  liable  to  heat  from  the  friction  of  the  journals. 

Question  858.  What  is  meant  by  the  term  “lost  motion  ” ? 

Answer.  It  is  used  to  designate  the  wear  of  machinery,  whicn  causes  a 
loss  of  motion  in  some  of  the  parts.  Thus,  if  the  bearings  of  the  main 
connecting-rods  are  worn,  the  piston  must  move  a distance  equal  to  the 
wear  at  each  end  of  the  stroke  before  it  moves  the  crank-pin.  Lost 
motion  might  therefore  be  called  the  looseness  of  the  parts.  When  we 
speak  of  taking  up  the  lost  motion,  we  mean  making  parts  which  were 
loose,  fit  tightly. 


CHAPTER  XVI. 


THE  VALVE-GEAR. 

Question  354.  What  is  meant  by  the  valve-gear  of  a locomotive  f 

Answer.  By  the  valve-gear  is  meant  the  arrangement  of  mechanism 
consisting  of  eccentrics,  rods,  links,  rockers,  etc.,  by  which  the  valves 
are  moved  and  their  motion  is  regulated. 

QUESTION  355.  What  is  required  of  the  valve-gear  in  working  a loco- 
motive ? 

Answer.  It  must  be  so  arranged  that  the  locomotive  can  be  run  either 
backward  or  forward,  and  so  that  the  motion  of  the  wheels  can  be  reversed 
quickly  and  with  certainty.  It  should  enable  the  runner  to  employ  the 
greatest  power  of  the  engine  by  admitting  steam  into  the  cylinders  dur- 
ing the  whole  or  nearly  the  whole  of  the  stroke  of  the  pistons,  or,  when 
less  power  is  required,  to  use  the  steam  more  economically  by  working  it 
expansively. 

Question  356.  How  is  the  valve-gear  constructed  so  as  to  run  the 
engine  backward  or  forward? 

Answer.  As  already  explained,  in  answer  to  Question  189,  two  eccen- 
trics are  provided  for  each  cylinder.  These  are  set  so  that  • one  of  each 
pair  will  run  the  locomotive  in  one  direction,  and  the  other  two  the 
reverse  way. 

Question  357.  How  must  the  eccentrics  for  each  cylinder  be  set  in  order 
that  the  one  may  run  the  engine  forward  and  the  other  backward? 

Answer.  This  can  be  best  explained  by  reference  to  fig.  241,  in  which 
the  piston,  P,  is  represented  at  the  beginning  of  the  backward  stroke, 
and  the  valve,  V,  has  the  requisite  lead,  and  is  just  about  to  open  the 
front  steam-port,  c.  It  is  obvious  that,  in  order  to  complete  the  backward 
stroke  of  the  piston,  the  front  port,  c,  must  be  opened  to  admit  steam  into 
the  front  end  of  the  cylinder,  and,  therefore,  the  valve  must  be  moved  in 
the  direction  indicated  by  the  dart,  a.  To  do  this,  the  upper  arm  of  the 
rocker,  R,  must  move  in  the  same  direction  indicated  by  the  dart,  a'  and 
the  lower  arm  must  be  moved  the  reverse  way,  as  indicated  by  the  dart,  b. 
If  the  crank  is  intended  to  move  in  the  direction  indicated  by  the  dart, 


282 


Catechism  of  the  Locomotive. 


N,  then  the  centre  of  the  eccentric,  J,  must  be  above  the  centre  of  the 
shaft  or  axle,  to  move  the  lower  end  of  the  rocker  in  the  direction  indica- 
ted by  the  darts,  b and  m.  Supposing,  however,  it  was  intended  to  move 
the  crank  the  reverse  direction,  as  shown  by  the  dart,  N,  in  fig.  242,  it  is 
evident  in  that  case  that  the  valve  must  be  moved  in  the  same  direction 
as  before,  to  open  the  front  steam-port,  c,  and  thus  admit  steam  to  force 
the  piston  back.  But  if  the  crank  turns  in  the  direction  shown  by  the 
dart,  N,  fig.  252,  then  the  centre  of  the  eccentric,  K , must  be  placed 
below  the  centre  of  the  axle  to  move  the  lower  rocker  arm  in  the  direction 
of  the  darts,  b and  n,  and  the  valve  in  that  indicated  by  a.  It  will  thus  be 
seen  that  the  centre  of  the  eccentric  for  running  forward  and  that  of  the 
one  for  running  backward  must  be  placed,  the  on e,J,  above  and  the  other, 
K , below  the  centre  of  the  axle  at  the  beginning  of  the  stroke  of  the 
piston,  as  shown  in  fig.  242. 

QUESTION  358.  Why  is  it  that  the  centres  of  the  eccentrics  are  not 
placed  opposite  to  each  other  on  the  axle  ? 

Answer.  Because  before  the  beginning  of  the  stroke  of  the  piston  it  is 
necessary  to  move  the  valve  from  its  middle  position  a distance  equal  to 
the  lap  before  the  steam-port  begins  to  open.  If  we  had  a valve  without 
any  lap,  the  centres  of  the  eccentrics  could  be  placed  at  right  angles,  or, 
as  mechanics  say,  “ square  ” with  the  crank,  and  exactly  opposite  to  each 
other,  because  such  a valve  would  begin  to  take  steam  as  soon  as  it  moved 
from  the  middle  of  the  valve-face.  But  if  we  have  a valve  like  that  shown 
in  fig.  67,  it  is  plain  that  before  it  will  admit  or  take  steam  as  it  is  called, 
in  either  of  the  steam-ports,  it  must  be  moved  from  the  centre  of  the 
valve-face,  or  its  middle  position,  a distance  equal  to  the  lap,  L.  For  this 
reason,  therefore,  the  eccentric,  instead  of  being  placed  at  half-throw*  as 
it  is  called,  must  be  so  far  ahead  of  the  middle  position  as  to  have  moved 
the  valve  a distance  equal  to  its  lap,  and  if  any  lead  is  given  to  the  valve, 
equal  to  the  lap  and  lead  together.  In  figs.  241,  242  and  243,  f g is  a ver- 
tical line  at  right  angles  to  the  crank  at  the  beginning  of  the  stroke.  It 
will  be  seen  that  the  centre  of  each  of  the  eccentrics  is  set  far  enough 
ahead  of  this  line  to  give  the  valve  the  required  lead.  When  the  piston 
reaches  the  back  end  of  the  cylinder,  the  two  eccentrics  will  occupy  the 
position  shown  in  fig.  243,  in  which  position  the  lower  one,  f,  would 
move  the  valve  so  as  to  turn  the  crank  in  the  direction  of  the  dart,  N,  and 
the  upper  one,  K , will  turn  it  in  the  reverse  direction.  It  will  be  seen 

* This  would  be  at  right  angles  to  the  crank  when  it  is  at  a dead  point,  and  the  piston  is  at 
the  end  of  the  stroke. 


Diagrams  of  Valve-Gear.  Scale  in.=l  ft. 


284 


Catechism  of  the  Locomotive. 


that  in  this  position  both  of  the  eccentrics  are  again  ahead  of  their  half- 
throw  when  the  piston  is  at  that  end  of  the  stroke. 

Question  359.  How  is  the  motion  of  either  eccentric  communicated  to 
the  valve  ? 

Answer . The  ends  of  each  pair  of  eccentric-rods  are  connected  to-. 


gether  by  a link,  a*b,  figs.  244,  245  and  246.  This  link  has  a curved 
groove  or  slot,  kt  in  it,  in  which  a block,  B,  fits  accurately,  so  that  it  can 
slide  freely  from  one  end  to  the  other.  This  block  is  attached  to  the 
lower  rocker-arm,  N,  Fig.  246,  by  a pin,  c,  which  works  freely  in  the 
block.  The  two  eccentric-rods,  C and  D,  are  attached  near  the  ends  of  the 
link,  at  e and  f,  by  pins  and  knuckle-joints.  It  is  apparent  that  if  the 
link  is  down,  or  in  the  position  shown  in  fig.  246,  and  also  in  the  diagram, 
fig.  247,  drawn  on  a smaller  scale,  the  motion  of  the  upper  eccentric-rod, 
which  is  usually  used  for  the  forward  motion,  will  be  imparted  to  the 
rocker,  and  thus  to  the  valve,  and  when  the  link  is  in  the  position  shown 
in  fig.  248  that  the  valve  will  be  moved  by  the  lower  or  backward  eccentric- 
rod,  D.  In  order  to  reverse  the  engine,  it  is  then  only  necessary  to 
provide  the  means  of  raising  and  lowering  the  link.  This  is  done  by  a 
shaft,  A,  fig.  246,  called  a lifting-shaft  which  has  two  horizontal  arms, 
E*  one  for  each  link,  and  a vertical  arm,  F.  Each  link  is  suspended 


Only  one  of  these  is  shown  in  the  engraving. 


Fig.  246.  Link-Motion,  Scale  1 in.=l  ft. 


286 


Catechism  of  the  Locomotive. 


from  the  end  of  one  of  the  horizontal  arms  by  a rod  or  bar,  g h,  called 
a link-hanger , which  is  connected  to  the  link  and  to  the  arm  above  by 
pins,  h and  g,  which  enable  the  hanger  to  vibrate  freely.  The  lower  pin 
is  attached  to  a plate,  op,  called  a link-saddle , which  is  bolted  to  the  link. 
The  vertical  arm,  F,  of  the  lifting-shaft  is  connected  by  a rod,  G G,  called 
the  reverse-rod,  to  a lever,  20  21,  Plates  III  and  IV,  in  the  cab  called  a 
reverse-lever,  the  construction  of  which  will  be  explained  hereafter.  This 
lever  is  worked  by  the  locomotive  runner,  and  by  moving  the  upper  end 
of  it  forward,  the  link  will  be  lowered  into  the  position  shown  in  fig.  246, 
and  also  in  the  diagram,  fig.  247,  and  the  rocker  and  valve  will  then  be 
moved  by  the  forward  eccentric;  and  if  the  reverse  lever  is  moved  back, 
the  link  will  be  raised  into  the  position  shown  in  fig.  248,  and  the  back- 
ward eccentric  will  then  move  the  valve.  When  this  is  done,  the  valve- 
gear  is  said  to  be  thrown  into  the  forward  or  backward  motion,  or  for- 
ward or  back  gear. 

Question  860.  How  is  the  steam  ?nade  to  work  more  or  less  expan- 
sively ? 

Answer.  By  changing  the  travel  of  the  valve. 

Question  361.  How  is  the  travel  of  the  valve  changed? 

Answer.  By  either  raising  or  lowering  the  link  so  that  the  link-block 
and  rocker-pin  will  be  some  distance  above  or  below  the  eccentric-rods. 
Thus  in  fig.  247,  the  motion  of  the  upper  eccentric-rod,  and  in  fig.  248 
that  of  the  lower  or  back  eccentric-rod  is  communicated  to  the  rocker-pin 
and  the  valve.  If,  however,  the  link  should  be  raised  so  that  the  link- 
block  and  rocker-pin  are  somewhat  below  the  upper  or  forward  eccentric- 
rod,  as  shown  in  fig.  249,  then  the  motion  imparted  to  the  rocker  and 
valve  will  partake  somewhat  of  that  of  the  upper  and  also  of  the  lower 
eccentric-rod.  So  long  as  the  rocker-pin  is  above  the  centre  of  the  link, 
the  motion  of  the  valve  will  partake  most  of  that  of  the  upper  or  forward 
rod,  and  the  engine  will  then  run  forward  ; but  when  the  rocker-pin  is 
below  the  centre  of  the  link  its  motion  will  be  influenced  more  by  the 
back  eccentric-rod,  and  the  engine  will  then  run  backward. 

The  motion  of  the  link,  which  is  somewhat  complex  and  difficult  to 
understand  clearly,  will  perhaps  be  understood  better  if  we  represent  it  in 
a number  of  successive  positions  of  the  whole  stroke  of  the  piston,  as  was 
done  to  show  the  motion  of  the  eccentric  in  figs.  30  to  43.  We  will  there- 
fore suppose  that  the  link  is  in  what  is  called  full-gear  forward,  as  shown 
in  figs.  251  to  262.  In  fig.  251  the  link  is  in  the  position  it  would  occupy 
when  the  piston  is  at  the  beginning  of  its  stroke  ; in  fig.  252  it  is  in  that 


Diagrams  of  Link-Motion.  Scale  in.- 1 ft, 


Diagrams  of  Link-Motion.  Scale  H ln.=l  ft. 


290 


Catechism  of  the  Locomotive. 


which  it  will  be  in  when  the  piston  has  moved  4 inches ; in  fig.  253,  when 
it  has  moved  8 inches;  in  fig.  254,  12;  and  in  figs.  255,  256  and  257,  16, 
20  and  24  inches.  Figs.  257  to  262  represent  the  successive  positions  of 
the  link  during  the  return  stroke. 

In  these  figures  the  centre-line  of  the  slot  in  the  link  is  represented  by 
dotted  lines,  which  are  indicated  by  numbers  preceded  by  a — or  + sign. 
The  numbers  represent  the  distance  that  the  piston  has  moved  from  the 
beginning  of  the  stroke,  when  the  link  is  in  the  position  shown,  and  the 
— sign  indicates  the  backward  stroke  of  the  piston,  and  the  + sign  its 
forward  stroke.  Thus  in  fig.  252  the  figures  — 4 — 4 indicate  the  dotted 
centre-line,  and  also  designate  that  the  piston  has  moved  4 inches  from 
the  beginning  of  its  backward  stroke ; when  the  link  is  in  the  position 
represented,  and  — 8 — 8,  in  fig.  253,  that  it  has  moved  8 inches  of  its 
backward  stroke.  To  show  the  action  of  the  link,  the  successive  positions 
of  the  centre-lines  represented  by  figs.  251  to  262  have  been  laid  down  on 
a larger  scale  in  the  diagram,  fig.  263.  For  greater  clearness  the  centre- 
lines are  represented  in  full  instead  of  by  dotted  lines,  and  are  indicated  by 
the  same  sign  and  numbers  in  the  diagram,  fig.  263,  that  were  used  in 
figs.  251  to  262. 

O,  fig.  263,  represents  the  rocker-shaft,  and  the  arc,  a b,  the  path  in 
which  the  centre  of  the  lower  rocker-pin  moves.  As  the  centre  of  the 
rocker-pin  is  always  in  the  centre-line,  a b,  fig.  245,  of  the  link,  it  is  evi- 
dent that  when  the  link  is  in  the  positions  shown  in  figs.  251  to  262,  and 
in  263,  that  the  rocker-pin  will  be  moved  from  a to  b by  the  action  of  the 
link,  or  a total  distance  of  5|-  inches. 

If,  however,  the  link  was  raised  up  into  the  position  shown  in  fig.  249, 
so  that  the  rocker-pin  is  half-way  between  the  end  of  the  eccentric-rod 
and  the  centre  of  the  link,  then  the  action  of  the  link  in  relation  to  the 
rocker  would  be  as  represented  in  fig.  264,  in  which  the  different  positions 
of  the  centre-line  of  the  link  and  of  the  rocker  have  been  laid  out  with 
the  link  raised  up  for  half-gear,  as  it  is  called,  in  the  same  way  as  was 
done  for  full-gear  before.  From  this  it  will  be  seen  that  the  travel,  a b , 
fig.  264,  imparted  to  the  rocker-pin  and  valve  by  the  link  when  it  is  in 
the  position  shown,  instead  of  being  5£  inches  is  now  only  3£  inches.  In 
fig.  250  the  link  is  represented  in  the  position  it  would  be  in  when  it  is 
raised  up,  so  that  the  rocker-pin  would  be  in  the  centre  of  it  or  midway 
between  the  eccentric-rods.  This  position  is  called  mid-gear.  The  suc- 
cessive positions  of  the  centre-line  of  the  link  in  this  position  have  been 
laid  down  in  fig.  265,  in  the  same  way  as  was  done  for  full  and  half-gear. 


+16 


Diagrams  of  Movement  of  Link.  Scale  *4  in.— 1 in. 


292 


Catechism  of  the  Locomotive. 


The  Valve  Gear. 


293 


The  movement  of  the  rocker,  it  will  be  seen  from  this  figure,  is,  for  mid- 
gear, only  2£  inches. 

These  diagrams  show  that  when  the  rocker-pin  is  opposite  the  eccentric- 
rod,  as  in  figs.  247  and  248,  the  valve  receives  the  full  or  more  than  the 
full  throw  of  the  eccentric,*  and  that  the  motion  imparted  by  the  eccentric 
diminishes  as  the  rocker-pin  approaches  the  centre  of  the  link,  as  in  figs. 
249  and  250,  so  that,  with  eccentrics  having  5 inches  throw,  and  a valve 
with  l lap  and  £ inch  lead,  we  can  increase  or  diminish  the  travel  of  the 
valve  from  2^  to  5|-  inches  by  simply  raising  or  lowering  the  link,  which  is 
done  by  the  reverse-lever. 

Question  362.  What  is  the  effect  of  this  variation  of  travel  on  the 
working  of  the  valve  and  the  admission  and  release  of  steani  to  and  from 
the  cylinder  ? 

Answer.  It  is  almost  precisely  the  same  as  that  which  is  effected  by 
increasing  or  diminishing  the  throw  of  an  eccentric,  which  was  explained 
in  the  answer  to  Question  147.  In  order  to  show  this  effect  more  clearly,, 
we  have  represented  by  motion-curves,  fig.  266,  the  movement  imparted 
to  the  valve  by  the  link  when  it  is  in  full,  half,  and  mid-gear,  as  illustrated 
in  the  preceding  figures.  The  curve  for  full-gear  is  engraved  in  full  heavy 
lines ; that  for  half-gear,  in  lighter  lines,  and  for  mid-gear,  in  dotted  lines. 

Question  363.  What  may  be  learned  from  these  motion-curves? 

Answer.  They  show  the  exact  motion  of  the  valve  in  relation  to  the 
steam  and  exhaust-ports  during  a complete  revolution  of  the  crank. 
Thus,  if  we  take  the  curve,  M N O P Q R S,  drawn  in  heavy  lines,  and 
which  represents  the  movement  of  the  outer  edge  of  the  valve  in  full-gear 
in  relation  to  the  port,  c,  it  will  show  first  the  lead  of  the  valve  at  M. 
Then  the  intersection  of  the  curve  with  the  inner  edge  of  the  port  above 
the  horizontal  line,  3 21',  shows  that  the  port,  c , is  then  wide  open.  The 
outer  edge  of  the  valve  then  moves  beyond  the  inner  edge  of  the  port, 
until  the  curve  gets  below  the  line,  16  8'.  The  horizontal  lines,  0 24',  1 
23',  2 22',  etc.,  represent  inches  of  the  stroke,  and  the  intermediate  lines 
divide  the  inches  into  eighths,  as  has  been  explained.  The  position  of 
the  curve  on  those  lines,  therefore,  indicates  that  of  the  valve  when  the 
piston  is  at  a corresponding  distance  from  the  beginning  of  its  stroke. 
The  diagram  shows  then  that  at  2|  inches  of  the  stroke  the  port,  c,  is  wide 

* When  the  block  is  opposite  the  eccentric-rod  at  the  beginning  of  the  piston  stroke,  the  link 
moves  it  a distance  somewhat  greater  than  the  throw  of  the  eccentric,  owing  to  the  fact  that 
when  the  link  assumes  the  inclined  position,  shown  in  figs.  206  and  207,  the  block  slips  upward 
in  the  link-slot.  This  slip  of  the  block  is,  however,  dependent  on  the  way  in  which  the  link  is 
suspended. 


Fig.  266.  Curves  Showing  Motion  of  Valve.  Scale  *4  m.=l  in. 


The  Valve  Gear. 


295 


open,  and  that  the  valve  begins  to  close  it  at  16f  inches  of  the  stroke. 
The  intersection  of  the  curve  with  the  outer  edge  of  the  port,  c,  below  the 
line,  21  3',  shows  that  this  port  is  then  closed,  or  the  steam  is  cut  off  by 
the  valve  when  it  is  working  in  full-gear. 

The  curve,  M'  N'  O’  P*  Q'  R'  S',  shows  the  movement  of  the  exhaust 
edge  of  the  valve.  It  will  be  seen  that  at  the  beginning  of  the  stroke,  as 
shown  at  M',  the  port,  d,  is  nearly  wide  open  for  the  escape  of  the  steam, 
which  is  in  the  back  end  of  the  cylinder.  The  intersection  of  the  curve 
with  the  outer  edge  of  the  port  a little  below  the  line,  20  4',  shows  that 
the  valve  has  then  commenced  to  close  the  port,  d,  and  another  intersec- 
tion with  the  inner  edge  below  the  line,  23  T,  indicates  that  it  is  entirely 
closed  before  the  piston  has  reached  the  end  of  the  cylinder.  The  steam 
which  remains  in  it  when  the  valve  closes  is  then  compressed  by  the  piston 
as  it  advances  to  complete  its  stroke.  For  this  reason  the  point  where 
the  valve  closes  the  port  to  the  exhaust  is  called  the  point  of  compression . 
If  we  follow  up  the  reverse  side  of  the  curve  it  will  be  seen  that  it  inter- 
sects the  inner  edge  of  the  port,  e , at  Z,  or  near  the  line,  1 23'.  This  shows 
that  the  port,  e,  is  opened  to  the  exhaust  before  the  piston  has  completed 
its  stroke.  This  is  called  the  point  of  pre-release. 

In  the  same  way  we  may  follow  the  curve,  M n o p q r S,  which  shows 
the  movement  of  the  valve  in  mid-gear.  It  shows  that  at  no  time  is  the 
port  wide  open,  and  steam  is  then  cut  off  at  about  15f  inches  of  the  stroke, 
and  that  the'curve,  M'  n'  o'  p'  q'  r’  S',  shows  that  the  valve  begins  to  close 
the  exhaust-port,  e,  to  the  exhaust  at  about  12  inches  of  the  stroke,  and 
that  compression  begins  at  about  21£  inches.  The"  intersection  of  the 
opposite  side  of  this  curve  with  the  inner  edge  of  the  port,  d,  at  z,  shows 
that  pre-release  or  exhaust  begins  while  the  piston  must  still  move  3£ 
inches  to  complete  its  stroke. 

The  dotted  lines,  M S and  M'  S',  show  the  motion  of  the  valve  in  mid- 
gear, and  the  curve  then  becomes  a straight  line.  The  greatest  opening 
of  the  steam-port,  for  the  admission  of  steam,  is  then  no  greater  than  the 
lead. 

It  is  of  course  possible  to  work  the  link  in  any  intermediate  position 
between  those  which  have  been  represented. 

Question  364.  What  is  the  greatest  and  the  least  admission  of  steam 
possible  with  the  ordinary  link  motion  ? 

Answer.  With  24  inches  stroke  of  piston  and  5|  inches  travel  and  | 
inch  lap,  steam  can  be  admitted  as  shown  by  the  motion-curves  during 
21£  inches,  or  nearly  90  per  cent,  of  the  stroke,  and  can  be  cut  off  at  about 


296 


Catechism  of  the  Locomotive. 


3 inches  or  12£  per  cent.  In  mid-gear  the  pre-admission  of  steam — that 
is,  the  admission  of  steam  before  the  piston  reaches  the  end  of  the  stroke, 
is  equal  to  that  admitted  after,  so  that  it  is  impossible  to  work  the  loco- 
motive with  the  link  in  that  position.  Practically  it  is  found  that  little 
useful  work  can  be  done  with  a link  if  the  steam  is  cut  off  at  less  than  6 
inches,  or  one-fourth  of  the  stroke.  Even  then  the  opening  of  the  steam- 
ports  is  so  small  that  the  steam  which  enters  the  cylinders  is  liable  to  be 
wire-drawn. 

Question  365.  How  are  the  curves  drawn  which  represent  the  motion 
of  the  valve  ? 

Answer.  These  motion-curves  as  produced  by  the  link-motion  are 
difficult  to  draw,  as  the  motion  of  the  link  is  very  complicated.  It  is 
doubtful,  therefore,  whether  those  who  have  no  knowledge  of  mechanical 
drawing  will  be  able  to  understand  the  following  description  of  the  method 
of  doing  it. 

In  the  first  place,  the  centre,  S,  fig.  267,  of  the  axle,  0 of  the  rocker, 
and  A of  the  lifting-shaft  must  be  laid  down  in  their  proper  positions.  If, 
now,  the  valve  has  £ inch  lap  and  lead,  it  must  be  Li  inch  from  its 
middle  position,  and  the  lower  rocker-pin,  c,  must  be  the  same  distance 
ahead  when  the  piston  is  at  the  front  end  of  the  cylinder  and  at  the 
beginning  of  the  backward  stroke.  We  will,  therefore,  mark  the  centre, 
c , of  the  rocker-pin  that  far  ahead  of  the  vertical  centre-line,  m n,  which 
represents  the  central  position  of  the  rocker. 

If  from  the  centre  of  the  axle  a circle,  op  q,  be  drawn,  whose  diameter 
is  equal  to  the  throw  of  the  eccentrics,  this  circle  will  represent  the  path 
in  which  the  centres  of  the  eccentrics  will  revolve. 

Another  circle,  H I J N,  whose  diameter  is  equal  to  the  stroke  of  the 
piston,  should  be  drawn  from  S,  as  a centre,  to  represent  the  path  of  the 
centre  of  the  crank-pin.  If  the  distance  from  the  centre,  S,  of  the  axle  to 
the  centre  of  the  lower  rocker-pin,  cr,  when  the  latter  is  in  its  middle 
position,  be  taken  for  a radius,  and  from  the  position,  c,  of  the  rocker- 
pin,  at  the  beginning  of  the  stroke,  as  a centre,  the  circle  representing  the 
path  of  the  eccentrics  be  intersected  at  two  points,  o and  p,  the  points  of 
intersection  will  represent  the  positions  of  the  centres  of  the  forward  and 
backward  eccentrics  at  the  beginning  of  the  stroke  of  the  piston.  Having 
determined  these  positions,  lay  off  a distance,  c e,  from  c,  the  centre  of  the 
rocker-pin,  equal  to  the  distance,  c e,  fig.  245,  of  the  centre-line  of  the 
link  from  the  centre  of  the  pin,  e,  by  which  the  eccentric-rod  is  connected 
to  the  link.  Then  the  distance,  e o,  fig.  267,  will  be  the  length  of  the 


Fig.  267.  Diagram  Showing  Method  of  Laying  Out  Motion  of  Valve.  Scale  1 in. — 1 ft. 


Fig.  268.  Diagram  Showing  Method  of  Laying  Out  Motion  of  Valve.  Scale  1 in.=l  ft. 


The  Valve  Gear. 


299 


eccentric-rod.  With  the  distance  as  a radius,  and  o and  p as  centres, 
describe  two  arcs,  1 2 and  V 2'.  Having  laid  down  the  position  of  the 
lifting-shaft,  A with  A g,  equal  to  the  length  of  the  lifting-arm,  E,  describe 
an  arc,  3 4.  As  the  link  is  suspended  from  g,  by  the  hanger,  g h,  which 
oscillates  from  the  end,  g,  of  the  lifting-arm  in  the  arc,  5 6,  and  as  the 
lifting-arm,  for  any  one  point  of  cut-off,  is  stationary,  therefore,  the  point 
of  suspension  of  the  link  must  always  be  on  the  arc,  5 6,  described  from 
the  centre  of  the  pin,  g,  in  the  lifting-arm,  with  a radius  equal  to  the 
length  of  the  hanger.  As  the  eccentric-rods  are  connected  to  the  link  by 
pins,  e and  f>  their  centres  must  always  coincide  with  the  arcs,  1 2 and  V 
2',  described  from  the  centres  of  the  eccentrics  by  the  length  between  the 
centres  of  the  eccentric-rods  as  a radius. 

To  locate  the  position  of  the  link,  a drawing  like  fig.  245  should  be 
made  on  a thin  board,  card  or  a stiff  piece  of  paper.  Then  cut  away  the 
portion  on  the  left  of  the  centre-line,  a b,  as  shownin  fig.  269,  so  as  to 


Fig.  269.  Template  of  Link.  Scale  1 an. =1  ft. 

leave  an  exact  outline  of  the  centre-line  of  the  link.  Draw  lines  through 
the  centres,  e and /,  of  the  pins  by  which  the  rods  are  attached  to  the  link, 
and  cut  off  the  portion  on  the  right-hand  side  of  these  lines.  As  the 
centre  of  suspension  is  usually  back  of  the  middle  of  the  link,  a notch 
should  be  made  on  the  front  side,  as  shown  at  h.  Having  cut  the  board 


300 


Catechism  of  the  Locomotive. 


or  paper  accurately  to  the  form  of  the  link,  lay  it  on  the  drawing,  fig.  267, 
so  that  the  centres,  e and  /,  will  be  on  the  arcs,  1 2 and  Y 2',  and  the  centre 
of  suspension,  h , will  be  on  the  arc,  5 6.  When  these  three  points  coincide 
with  the  three  arcs,  the  template  will  be  in  the  position  that  the  link 
would  occupy  when  it  is  suspended  from  the  point,  g,  and  the  centres  of 
the  eccentric  are  in  the  position  shown.  When  the  position  of  the  link 
is  thus  determined,  draw  a line  on  the  edge,  a b,  to  represent  the  centre- 
line of  the  link  in  that  position. 

Another  position  of  the  link  may  be  laid  out  as  follows  : By  the  method 
described  in  answer  to  Question  143,  lay  down  the  position,  N',  fig.  268, 
of  the  crank-pin  when  the  piston  has  moved  any  distance,  say  4 inches  of 
its  stroke.  Lay  out  the  position  of  the  centres,  o and  p,  of  the  eccentrics, 
the  same  as  in  fig.  267,  and  draw  lines,  Soy  and  S p 8,  from  the  centre,  S, 
of  the  axle  through  the  centres,  o and  p,  and  intersecting  the  circle,  H I J 
N,  at  7 and  8. 

Now,  the  crank-pin  turns  from  Wto  N',  while  the  piston  is  moving  4 
inches  from  the  front  end  of  the  cylinder.  This  is  called  its  angular  mo- 
tion. As  the  crank  and  eccentrics  are  all  fastened  to  the  axle,  they  must 
all  have  an  equal  angular  motion  while  the  crank-pin  is  moving  from  N 
to  N'.  Therefore,  if  with  a pair  of  dividers  we  take  the  distance,  N N', 
and  lay  it  off  from  7 to  9,  and  from  8 to  10,  and  draw  lines  from  9 and  10 
to  the  centre,  S,  of  the  axles,  the  intersection  of  these  lines  at  o'  and  p'y 
with  the  circle,  o p q,  will  represent  the  angular  motion  of  the  eccentrics, 
while  the  crank-pin  is  moving  from  N to  N',  and  o’  and  p’  will  be  the  posi- 
tion of  the  centres  of  the  eccentrics  when  the  crank-pin  is  at  N\  From 
these  centres,  with  the  length  of  the  eccentric-rods  as  a radius,  describe 
the  arcs,  1 2 and  1'  2',  as  before.  Draw  the  arc,  5 6,  as  in  fig.  267,  and  then 
lay  the  template  of  the  link,  fig.  269,  on  the  drawing,  and  make  its  centres, 
h e and  f,  coincide  with  these  arcs  as  before,  and  it  will  then  represent  the 
position  of  the  link  when  the  piston  has  moved  4 inches,  and  the  crank- 
pin  is  at  N'.  A line  drawn  along  the  edge,  a b,  will  represent  this  position 
of  the  centre-line  of  the  link.  This  process  can  be  repeated  for  successive 
positions  of  the  piston  and  crank-pin. 

Such  diagrams  as  have  been  described  should  be  drawn  to  a larger  scale 
than  the  engravings — preferably  full  size — and  great  care  must  be  taken 
to  lay  them  out  with  the  greatest  precision.  A thin,  white  pine  board — 
about  A inch  thick — is  the  best  material  to  make  the  template  of  the 
link  of.  The  outline,  a b,  must  conform  accurately  to  the  centre-line  of 
the  link. 


The  Valve  Gear. 


30J 


Question  366.  Having  laid  out  the  successive  positions  of  the  link , as 
shown  in  figs.  263-265 , how  are  the  motion-curves , fig.  266,  drawn  from 
them  ? 

Answer.  In  fig.  263  the  arc,  a b,  represents  the  path  of  the  centre  of 
the  rocker-pin,  and  the  dotted  line,  0 c,  the  middle  position  of  the  lower 
rocker-arm  but  on  a larger  scale  than  figs.  267  and  268.  The  distance  from 
c of  the  point  of  intersection,  o,  of  the  line,  — o — o,  with  the  arc,  a b,  repre- 
sents the  movement  of  the  valve  from  its  middle  position,  when  the  pis- 
ton is  at  the  beginning  of  its  backward  stroke.  In  fig.  266  the  dotted 
lines  at  m and  m',  represent  the  position  of  the  valve  in  the  middle  of  the 
valve-face,  the  lines,  m and  m'  representing  the  outer  or  steam  edge  and 
the  inner  or  exhaust  edge  of  the  valve.  As  the  valve  will  be  moved  a dis- 
tance equal  to  o c,  fig.  263,  from  its  middle  position  when  the  piston  be- 
gins its  stroke,*  and  as  the  movement  is  reversed  in  direction  by  the 
rocker,  if  we  lay  off  on  the  right  side  of  m and  m\  distances  m M and 
ml  M’y  the  points,  M and  M',  will  represent  the  position  of  the  edges  of 
the  valve  at  the  beginning  of  the  stroke.  From  m and  m’ , vertical  lines, 
m t and  m' t',  are  drawn  to  represent  the  position  of  the  two  edges  of 
the  valve  when  it  is  in  the  middle  of  the  valve-face  for  all  points  of  the 
stroke. 

Proceeding  as  before,  in  fig.  263,  the  distance  from  c of  the  point  of  inter- 
section, 4,  of  the  line,  — 4 — 4,  with  the  arc,  a b,  represents  the  move- 
ment of  the  valve  from  its  middle  position  when  the  piston  has  moved  4 
inches  of  its  stroke.  Taking  this  distance  and  laying  it  off  from  the  ver- 
tical lines,  m t and  m' t' , on  the  horizontal  line,  4 20',  of  fig.  266,  we  locate 
the  points,  A^and  N',  which  represent  the  positions  of  the  steam  and  ex- 
haust edges  of  the  valves  when  the  piston  has  moved  4 inches.  I11  the 
same  way  the  distance  from  c of  the  intersections  of  the  lines,  — 8 — 8, 
— 12  — 12,  — 16  — 16,  etc.,  in  fig.  263,  with  the  arc,  a b,  can  be  laid 
down  on  the  horizontal  lines,  8 16',  12  12',  16  8',  etc.,  of  fig.  266,  and  the 
points,  O P Q,  etc.,  and  O'  P’  Q , etc.,  are  thus  located.  The  curves,  M 
N O P Q R S,  and  M'  N'  O'  P'  Q'  R'  S',  can  then  be  drawn  through  these 
points  either  by  hand  or  by  constructing  wooden  templates,  and  the  inter- 
section of  these  curves  with  the  immediate  horizontal  lines,  in  fig.  266, 
will  represent  the  position  of  the  steam  and  exhaust  edges  of  the  valve  in 
relation  to  the  ports,  eg  and  e,  for  any  part  of  the  stroke  of  the  piston. 
The  more  points  there  are  determined,  the  more  accurate  will  be  the 


* This  will  be  the  case  when  the  two  arms  of  the  rocker  are  of  the  same  length,  as  they 
usually  are,  but  sometimes  they  are  of  different  lengths, 


m 3 . Catechism  of  the  Locomotive. 

'i 

» 

curves.  Ifc  is,  therefore,  best  to  lay  down  the  position  of  the  valve  for 
each  inch  of  the  stroke  of  the  piston.  The  curves  for  the  return  stroke 
of  the  piston  can  be  completed  by  drawing,  S T M,  and  S'  T'  M',  in  the 
same  way. 

The  curves,  M n o ft  q r S,  and  M ' n ' o'  ft,  q’  r'  S',  which  shows  the 
motion  of  the  valve  when  the  link  is  in  half-gear  forward,  or  M S,  M’  S', 
which  show  it  in  mid-gear,  may  be  drawn  in  the  same  way  from  the  dia- 
grams, figs.  264  and  265,  which  represent  the  successive  positions  of  the 
centre-line  of  the  link  when  it  is  in  half  and  mid-gear  forward. 

In  the  illustrations  the  upper  and  lower  rocker-arms  are  represented  as 
of  the  same  length,  as  already  explained ; in  some  cases  they  are  of  un- 
equal lengths,  which  of  course  affects  the  motion  of  the  valve.  In  the 
diagram,  figs.  267  and  268,  the  lower  rocker-pin,  c,  is  represented  as  being 
on  the  horizontal  centre-line,  A N I,  drawn  through  the  centre,  S,  of  the 
axle.  Usually  the  lower  rocker-pin  is  located  below  this  horizontal  centre- 
line, so  that  the  link  will  not  strike  the  boiler  when  it  is  raised  up  to  the 
back-gear. 

Question  367.  Is  there  any  other  method  of  drawing  these  motion- 
curves  ? 

Answer.  Yes;  models  which  show  the  working  of  the  valve-gear  have 
been  constructed,  to  which  the  reciprocating  motion  of  the  valve  is  im- 
parted, and  which  traces  a curve  with  a pencil  on  the  surface,  having  the 
same  motion  as  the  piston.  This  method  has  been  employed  by  the 
writer  in  an  instrument  which  he  has  applied  to  the  locomotive  itself. 
The  principle  upon  which  it  works  will  be  understood  by  supposing  that 
the  steam  and  exhaust-ports,  as  represented  in  the  diagram  for  motion- 
curves,  fig.  266,  be  drawn  on  a board,  A B C D,  fig.  270 ; but  instead  of 
standing  vertical,  as  in  fig.  266,  the  ports  are  represented  in  a horizontal 
position,  and  the  board  on  which  they  are  drawn  is  fastened  to  the  cross- 
head, L , so  that  the  former  will  move  backward  and  forward  simultane- 
ously with  the  latter  and  the  piston.  A small  shaft,  F,  is  attached  to 
suitable  supports,  j,  which  are  fastened  to  the  guide-bars.  This  shaft  has 
two  arms,  G and  E,  one  vertical  and  the  other  horizontal  and  of  the  same 
length.  The  upper  end  of  the  vertical  one,  G,  is  attached  to  the  valve- 
stem  or  the  rocker-arm  by  a short  connecting-rod,  H,  or  other  suitable 
means,  so  that  the  movement  of  the  upper  rocker-pin  and  the  valve-stem 
will  be  imparted  to  the  arm  and  shaft.  The  end,  P,  of  the  horizontal 
arm,  E,  then  has  exactly  the  same  motion  vertically  that  the  valve-stem 
and  valve  have  horizontally,  with  the  very  trifling  inaccuracy  due  to  the 


304 


Catechism  of  the  Locomotive. 


fact  that  the  movement  of  the  one  is  in  a straight  line,  whereas  the  other 
is  now  in  the  arc  of  a circle. 

Now,  if  a pencil,  P,  is  attached  to  the  end  of  the  horizontal  arm,  E,  and 
is  set  so  that  its  point  indicates  the  exact  position  of  the  steam  edge,  M, . 
of  the  valve,  as  shown  in  fig.  266,  it  is  obvious  that  when  the  piston  and 
board  have  moved  4 inches,  the  pencil  will  have  moved  downward  and 
have  drawn  the  portion  of  the  motion-curve  from  h to  i ; and  when  the 
piston  has  moved  8 inches  the  curve  will  be  drawn  to  j,  and  12,  16,  20 
and  24  inches  of  the  stroke  the  curve  will  be  drawn  to  k l m and  n , Dur- 
ing the  return  stroke  a corresponding  curve,  n o h,  will  be  drawn.  With 
such  an  instrument  curves  can  be  drawn  for  any  position  of  the  link,  and 
they  will  show  the  exact  movement  of  the  valve  during  the  whole  stroke, 
and  will  indicate  all  the  defects  resulting  from  bad  proportions  or  con- 
struction, lost  motion  in  the  parts,  or  other  causes  of  error  or  irregularity. 

In  using  this  instrument,  however,  it  is  usually  impracticable  to  attach 
a board  to  the  inside  of  the  cross-head,  and  it  must  therefore  be  fastened 
to  the  outside.  The  horizontal  arm,  E,  should  be  made  of  thin  steel,  so 
as  to  form  a spring.  The  end  has  a small  boss*  P,  with  a hole  in  it  T\ 
inch  in  diameter.  This  hole  has  a screw-thread  cut  in  it,  into  which  an 
ordinary  hard  drawing-pencil  is  screwed.  The  spring  is  so  arranged  that 
the  pencil  will  not  be  in  contact  with  the  board  unless  it  be  pressed 
against  it.  The  locomotive  is  then  placed  on  a smooth  piece  of  track 
with  steam  on  and  run  very  slowly,  so  that  a person  walking  alongside 
can  press  the  pencil  against  the  surface  of  the  board,  which  should  be 
covered  with  drawing-paper.  By  watching  the  cross-head  when  it  reaches 
the  end  of  the  stroke,  the  pencil  can  then  be  pressed  against  the  paper 
and  kept  in  contact  through  the  whole  stroke  and  instantly  released 
when  the  motion-curve  is  completed.  The  link  can  then  be  placed  in 
another  position,  and  thus  any  number  of  curves  can  be  drawn,  which  will 
furnish  an  accurate  means  of  analyzing  the  motion  of  the  valve. 

In  practice  it  is  best  not  to  draw  the  lines  which  represent  the  edges  of 
the  ports  until  after  the  curves  are  drawn  and  the  paper  removed  from 
the  board.  A line  must,  however,  be  drawn  on  the  engine  from  which  to 
lay  off  the  ports.  This  can  be  done  by  placing  the  valve  in  its  middle 
position,  and  then  fastening  the  shaft,  F,  with  a nut  which  should  be 
provided  for  that  purpose  on  its  end.  After  it  is  fastened  in  this 
position,  detach  the  connecting-rod,  H,  and  with  one  stroke  of  the  piston 
a straight  line  can  be  drawn  with  the  pencil,  P.  This  line  will  correspond 


* The  term  “ boss  ” is  used  to  imply  an  enlargemet  or  increased  thickness  of  any  part. 


The  Valve  Gear. 


305 


with  the  vertical  line,  m t or  m' t' , fig.  266,  and  from  it  the  ports,  c or  d, 
can  be  laid  off  so  that  the  motion-curves  will  represent  the  movement  of 
either  the  steam  or  exhaust  edges  of  the  valve  in  relation  to  the  ports. 

The  valve  can  be  placed  in  its  middle  position  by  putting  the  link  in 
mid-gear  and  marking  on  the  valve-stem  its  extreme  movement  each  way 
at  the  stuffing-box  of  the  valve-stem.  Subdivide  this  distance  on  the  valve- 
stem  and  move  the  subdivision  to  the  point  where  the  marks  were  made. 
The  valve  will  then  be  in  the  middle  of  the  valve-face,  if  the  valve  is  set 
correctly. 

Question  368.  Can  the  position  of  each  edge  of  the  valve , with  any 
given  amount  of  travel,  be  shown  in  its  relation  to  the  ports  by  one  motion- 
curve,  or  is  it  necessary  to  draw  such  curves  for  each  edge  of  the  valve  ? 

Answer.  One  motion-curve  is  sufficient  to  represent  the  movement  of 
any  part  of  the  valve  in  relation  to  the  ports  during  its  entire  travel.  This 
will  be  apparent  if  it  is  remembered  that  the  movement  of  any  portion  of 
the  valve  is  exactly  the  same  as  that  of  every  other  part,  and  therefore 
the  curve  which  represents  the  motion  of  one  part  is  exactly  like  that 
which  represents  the  movement  of  any  other  part.  This  is  shown  in  fig. 
266,  in  which  the  two  sets  of  curves,  M S and  M'  S',  are  exactly  alike. 
Therefore,  all  that  is  needed  to  show  the  movement  of  any  part  of  the 
valve  in  relation  to  the  ports  is  to  draw  lines  to  represent  the  ports  in 
their  relative  positions  to  the  valve.  In  this  way  one  curve  can  be  made 
to  show  the  movements  of  all  the  parts  of  the  valve  in  relation  to  the 
ports  below  it.  To  illustrate  this,  it  will  be  assumed  that  a motion-curve, 
M N O P Q R S T,  fig.  271,  which  represents  the  maximum  travel  of  a 
valve,  has  been  drawn  with  the  instrument  described  in  answer  to  the 
previous  question.  When  this  curve  has  been  drawn,  it  will  be  supposed 
further  that  the  crank-pin  has  been  placed  on  the  forward  dead-centre, 
and  the  shaft,  F,  fig.  276,  has  been  fastened  by  a nut  provided  for  that 
purpose  in  the  position  it  then  occupies,  and  that  the  connecting-rod.  H, 
is  detached  from  the  arm,  G,  and  by  a stroke  of  the  piston  the  pencil,  P, 
has  drawn  a straight  line,  Ms,  fig.  271.  This  line  will  represent  the  posi- 
tion of  any  part  of  the  valve  when  the  crank  is  on  the  front  centre,  and 
the  curve  will  represent  the  movement  and  position  of  the  same  part  dur- 
ing one  revolution  of  the  crank-pin.  It  will  be  supposed  that  the  line,  M 
s,  represents  the  position  of  the  steam-edge,  M,  fig.  266,  of  the  valve  at 
the  beginning  of  the  stroke.  Usually,  when  a valve  worked  by  a link 
motion  has  its  greatest  travel,  it  has  no  lead  at  the  beginning  of  its  stroke, 
but  its  edge  conforms  to  that  of  the  steam-port,  or,  as  it  is  expressed,  it  is 


Fig.  271.  Curve  Showing  Motion  of  Valves.  Scale  J4  in.=l  in. 


308 


Catechism  of  the  Locomotive. 


set  “ line-and-line  ” with  the  port.  If  that  is  the  case,  the  line,  M s,  fig. 

271,  will  represent  the  edge  of  the  steam-port.  If  the  valve  has  lead,  then 
a line  drawn  parallel  to  Ms,  at  a distance  from  it  equal  to  the  lead,  will 
represent  the  edge  of  the  port.  In  fig.  272  the  valve  is  shown  with  inch 
lead,  and  another  line,  a b,  has  been  drawn  at  a distance  from  M s,  equal 
to  the  width  of  the  port,  c,  fig.  266.  The  curves,  M N O P Q R S and 
M n o ft  q r S,  then  represent  the  motion  of  the  valve  in  relation  to  the 
port,  c,  in  the  same  way  as  it  is  shown  in  fig.  266. 

It  has  already  been  explained  that  the  movement  of  the  edges  M anv\ 
M'  of  the  valve,  and  the  two  sets  of  curves  in  fig.  266,  are  exactly  alike. 
They  differ  from  each  other  only  in  their  relation  to  the  ports,  c and  d. 
The  steam-edge,  M,  it  will  be  seen,  is  of  an  inch — equal  to  the  lead — 
from  the  line,  M s,  or  the  edge  of  the  port,  c,  whereas  the  exhaust-edge, 
M',  is  1 inch  from  in'  t’ , the  inner  edge  of  the  port,  d.  If,  then,  in  fig.  272, 
we  draw  a line,  in'  i',  1 inch  from  M,  and  another,  h z,  at  a distance  from 
m' t' , equal  to  the  width  of  the  port,  d,  fig.  266,  and  parallel  to  M s,  and 
assume  that  M,  fig.  272,  represents  the  exhaust-edge  of  the  valve,  then  the 
relation  of  the  two  curves  to  the  lines,  m'  t’  and  h z,  will  represent,  in  fig. 

272,  the  motion  of  the  exhaust  sides  of  the  valve,  in  the  same  way  as  it  is 
shown  by  the  curves,  M'  N'  O'  P'  Q'  R'  S'  and  M’  n’  o'p'  q'  r'  S',  in  fig. 
266.  Thus  the  one  set  of  curves  will  represent  the  motion  of  the  valve  in 
relation  to  both  of  the  steam-ports  during  the  backward  stroke  of  the 
piston.  It  remains  to  show  its  motion  during  its  forward  stroke. 

It  will  be  understood  if  a line,  K S,  fig.  271,  is  drawn  at  a distance  from 
M s,  equal  to  the  width  of  the  steam-port,  that  when  the  crank-pin  is  on 
the  dead  centre  and  the  piston  at  the  back  end  of  the  stroke,  that  the  line 
will  represent  the  position  of  the  edge  of  the  valve  when  the  piston  is  in 
that  position  or  is  at  the  beginning  of  the  forward  stroke,  just  as  Ms 
represented  it  at  the  beginning  of  the  backward  stroke.  A vertical  line, 
L' , is  therefore  drawn  below  the  horizontal  line,  L'  s,  to  represent  the 
steam-edge,  L',  fig.  266,  of  the  valve.  In  fig.  273,  the  line,  L! , has  been 
laid  down  in  the  same  position  as  in  fig.  271,  but  the  line,  K L' , has  been 
drawn  of  an  inch  from  L' , to  represent  the  lead  of  the  valve,  and 
another  line,  k l,  is  drawn  parallel  to  it  at  a distance  equal  to  the  width  of 
the  port,  d,  fig.  266.  If  this  is  done,  the  relation  of  the  curves,  S T J/and 
s t M,  in  fig.  273,  will  represent  the  movement  of  the  steam-edge,  L' , fig. 
266,  of  the  valve  in  relation  to  the  port,  d,  just  as  the  movement  of  M is 
shown  in  fig.  272. 

To  show  the  motion  of  the  exhaust-edge,  M',  fig.  266,  in  relation  to  the 


The  Valve  Gear. 


309 


port,  d,  a line,  A B,  is  drawn  in  fig.  273,  1 inch  from  L' , or  in  the  same 
relative  position  to  L'  that  i?i'  t ' occupies  to  M'  in  fig.  266.  Another 
dotted  line,  a'  b' , is  drawn  in  fig.  273,  at  a distance  from  A B equal  to  the 
width  of  the  port,  d,  fig.  266.  The  relation  of  the  curves,  STM  and  s t 
M,  fig.  273,  to  these  dotted  lines  will  show  the  motion  of  the  exhaust- 
edge,  M' , of  the  valve  to  the  port,  d , fig.  266,  just  as  that  of  M,  was  shown 
in  fig.  272.  It  will  require  no  explanation  to  show  that  by  drawing  the 
dotted  lines,  m' t'  and  h z,  in  fig.  272,  the  two  diagrams,  figs.  272  and  273, 
can  be  combined  in  one,  as  shown  in  fig.  272,  and  in  that  way  the  movement 
of  the  valve  in  relation  to  each  of  the  steam  and  of  the  exhaust-port  may  be 
shown  during  a complete  revolution  of  the  crank  by  one  set  of  motion- 
curves. 

In  this  diagram  the  motion  of  the  edge,  M,  of  the  valve  in  relation  to 
the  dotted  lines,  m' t'  and  h z,  shows  the  action  of  the  valve  in  the  exhaust 
side,  and  the  motion  of  M,  in  relation  to  the  lines,  Ms  and  a b,  its  action 
in  controlling  the  admission  of  steam.  In  fig.  274,  c and  d represent  the  two 
steam-ports,  but  their  relative  position  is  reversed  from  that  in  which 
they  actually  are,  as  shown  in  fig.  266.  The  relation  of  the  edge,  M,  of 
the  valve  to  the  dotted  vertical  lines  shows  its  action  on  the  exhaust  side. 
If  desirable,  the  inner  edges  of  the  exhaust-port,  g,  of  fig.  266,  could 
also  be  laid  down  on  the  diagram,  so  that  the  motion  of  the  valve  with 
reference  to  them  would  be  shown. 

If  the  reader  will  cut  a paper  section  of  a valve,  like  that  shown  in  fig. 
69,  and  place  the  different  edges,  a f and  bt  so  that  they  will  successively 
correspond  with  the  line,  M,  in  fig.  274,  the  diagram  will,  perhaps,  be 
more  clear.  If,  for  example,  the  paper  section  be  placed  to  the  right  of 
the  line,  M,  so  that  its  edge,  a,  will  correspond  with  M,  then  it  will  be 
seen  that  the  port,  c,  occupies  the  same  relation  to  it  that  it  does  in  fig. 
266.  If  the  valve  be  placed  so  that  the  edge,  b , corresponds  with  M,  then 
it  will  be  in  the  same  relation  to  the  port  indicated  by  the  dotted  lines,  m' 
t'  and  h z,  that  it  has  to  d,  in  fig.  266. 

Diagrams  of  this  kind,  which  are  made  full  size,  will,  of  course,  show  the 
movement  of  the  valve  more  distinctly  than  is  possible  in  the  space  occu- 
pied by  the  illustrations  herewith.  When  they  are  made  full  size,  the 
lines  indicating  the  ports  should  be  drawn  of  different  colors,  so  as  to 
distinguish  them  from  each  other  easily.  Such  diagrams  will  show  the 
position  of  the  valve  in  relation  to  the  ports,  and  indicate  the  distribution 
of  the  steam  during  the  whole  stroke.  It  is  only  necessary  to  refer  the 
curve  to  the  proper  line  to  determine  the  position  of  the  valve  in  relation 


Fig.  274.  Curves  Showing  Motion  of  Valve.  Scale  in.— 1 in. 


The  Valve  Gear. 


311 


to  either  of  the  ports  for  either  the  admission  or  release  of  steam.-  If,  for 
example,  we  want  to  observe  how  the  admission  of  steam  is  governed  by 
the  valve,  by  referring  to  fig.  274,  we  see  that  at  the  beginning  of  the 
backward  stroke  the  valve  has  tV  inch  lead  ; that  at  2i  inches  of  the 
stroke  the  port,  c,  is  wide  open,  as  shown  by  the  intersection  of  the 
motion-curve  with  the  line,  a bat  x ; that  the  valve  has  received  its  maxi- 
mum backward  travel  at  10  inches  of  the  stroke,  and  begins  to  close  the 
port  at  16£  inches,  and  completely  closes  it  at  21f  inches  of  the  stroke.  By 
referring  the  motion-curve  to  the  lines,  K L'  and  k /,  we  see  that  the 
valve  as  shown,  L'  again  has  inch  lead  at  the  beginning  of  the  forward 
stroke;  that  the  steam-port  is  wide  open  at  If  inches  of  the  stroke; 
begins  to  close  at  16f  inches,  and  is  completely  closed  at  21f  inches.  By 
referring  the  curve  to  the  line,  in'  t'  and  h i,  we  see  that  the  front  port 
begins  to  open  to  the  exhaust  before  the  piston  has  completed  its  forward 
' stroke,  that,  as  shown  at  c,  it  is  wide  open  almost  immediately  after  the 
piston  begins  its  stroke,  does  not  begin  to  close  until  the  piston  has  moved 
20  inches  of  its  stroke,  and  is  completely  closed  at  28f  inches  of  the  stroke. 
By  referring  the  curve  to  the  lines,  a'  b'  and  A B,  almost  the  same  phe- 
nomena will  be  observed  for  the  forward  stroke  of  the  piston.  In  fact,  from 
such  a diagram  the  whole  motion  of  the  valve  can  be  studied  and  analyzed 
with  the  greatest  accuracy ; and,  as  has  already  been  shown,  the  motion 
imparted  to  a slide-valve  by  a link  is  of  so  complicated  a nature  that  it  is 
almost  or  quite  impossible  to  observe  its  exact  nature  without  diagrams 
of  some  kind. 

Question  369.  Can  a diagram  be  constructed  to  represent  the  motion 
of  the  valve  with  different  amounts  of  travel? 

Answer.  Yes.  In  figs.  272,  273  and  274  two  motion-curves  are  shown, 
one  in  heavy  and  the  other  in  light  lines.  It  is  only  necessary  to  con- 
struct motion-curves  for  the  same  diagram  for  each  distance  traveled,  and 
they  will  show  the  movement  of  the  valve  for  the  given  amount  of  travel 
represented  by  the  curves.  Fig.  275  is  a reduced  copy  of  a series  of  mo- 
tion-curves taken  from  a locomotive.  From  this  diagram  the  movement 
of  a slide-valve  worked  by  the  link-motion  can  be  seen  from  the  highest 
to  the  lowest  practicable  point  of  cut-off.  For  convenience  of  reference 
the  curves  have  been  numbered. 

The  smallest  travel  of  the  valve  represented  by  curve  No.  1 is  a little 
less  than  2\  inches,  and  the  ports  are  then  opened  only  about  f inch,  and 
the  steam  is  cut  off  at  8 inches  on  the  backward  and  6f  inches  on  the  for- 
ward stroke.  The  exhaust  is  opened  or  the  steam  is  released  during  the 


The  Valve  Gear. 


313 


backward  stroke  at  17  inches,  and  during  the  forward  stroke  at  16f. 
When  the  valve  works  with  its  greatest  travel,  as  represented  by  curve  8, 
it  travels  5 inches,  and  opens  the  steam-port  wide  at  3-J-  inches  of  the 
backward  stroke  and  2J  inches  of  the  forward  stroke.  The  steam  is  cut- 
off at  20f  and  20^  inches,  and  its  release  takes  place  at  23£  inches  of  each 
stroke.  The  following  table  gives  the  greatest  width  of  opening,  the 


No.  of  Curves. 

Travel  of  Valve. 

Width  of  Opening 
of  Steam-Port. 

Point  of  Cut-Off. 

Point  of  Release. 

Lead.  J 

Back- 

ward 

Stroke. 

For- 

ward 

Stroke- 

Back- 

ward 

Stroke. 

For- 

ward 

Stroke. 

Back- 

ward 

Strpke. 

For- 

ward 

Stroke. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

1 

2% 

TB 

8 

6% 

17 

16% 

35 

2 

2% 

TB 

M 

9% 

9% 

18% 

18ts 

% 

3 

2% 

TB 

% 

12 

11% 

19% 

19te 

33 

4 

3% 

M 

14 

14 

20U 

20tb 

TB 

5 

3% 

Vs 

§1 

16% 

16% 

21H 

21% 

33 

6 

4 

1% 

1 3? 

m 

18% 

22% 

22% 

% 

7 

4% 

M 

m 

19% 

19% 

22y§ 

22% 

33 

8 

5 

m 

m 

20% 

20% 

23% 

23% 

TB 

point  of  cut-off,  the  point  of  release,  and  the  lead  for  a series  of  motion- 
curves.  This  table  was  made  up  from  the  motion-curves  drawn  with  an 
instrument  like  that  described  in  answer  to  Question  367,  on  a locomo- 
tive which  had  been  running  about  eighteen  months  and  whose  valve- 
gear,  consequently,  was  considerably  worn,  as  was  indicated  by  the  flatness 
of  the  motion-curves  on  each  side  at  the  point  where  the  motion  of  the 
valve  was  reversed.  This  flatness  was  caused  by  the  lost  motion  in  the 
valve-gear,  the  pencil  remaining  for  a time  stationary  when  the  motion 
was  reversed  and  while  the  parts  were  moving  from  their  bearings  on  the 
one  side  to  those  on  the  other.  The  curves  and  the  table,  therefore, 
showed  the  operation  not  of  a theoretically  perfect  valve-gear,  but  are 
examples  of  actual  practice,  with  such  imperfections  as  are  incidental  to 
ordinary  locomotives.  It  will  be  seen  that  the  instrument  shows  not  only 
what  the  valve-gear  should,  but  what  it  actually  does  do,  and  delineates 
all  its  imperfections. 

QUESTION  370.  What  are  the  chief  dimensions  of  the  valve-gear  whose 
motion  is  represented  in  fig.  275  ? 


314 


Catechism  of  the  Locomotive.. 


Answer.  The  throw  of  eccentrics  was  5 inches,  the  steam-ports  were 
inches,  and  the  exhaust-port  2f  inches  wide,  the  valve  had  £ inch  out- 
side and  7V  inside  lap  and  inch  lead  at  full  stroke. 

QUESTION  371.  What  relation  is  there  between  the  distance  which 
the  ports  are  opened  by  the  valve  and  its  travel  when  worked  by  a 
link? 

Answer.  As  explained  in  answer  to  Question  147,  the  width  which  the 
steam-ports  are  opened  by  the  valve  for  the  admission  of  steam  dimin- 
ished with  the  travel  of  the  valve.  This  is  shown  very  clearly  by  the  mo- 
tion-curves and  also  in  the  above  table,  from  both  of  which  it  will  be 
seen  that  when  the  valve  travels  only  2-|  inches  the  steam-ports  are 
opened  only  M inch  for  the  back  stroke  and  T5¥  for  the  front.  With  2-f 
travel  the  opening  is  T7T  and  LI  inch.  With  4 inches  travel  the  port  is 
opened  1^  and  1^  inches,  and  with  4£  inches  travel  they  would  be  opened 
wide.  With  4L  and  5 inches  travel,  as  will  be  seen  from  the  motion 
diagram,  the  ports  are  not  only  opened  wide,  but  the  valve  throws  “over” 
them,  or  travels  beyond  their  inner  edges. 

Question  372.  How  is  the  point  of  cut-off  affected  by  the  link? 

Answer.  Changing  the  travel  of  a valve  with  a link  has  a very  similar 
effect  to  that  produced  by  eccentrics  of  different  throw — that  is,  the  period 
of  admission  is  increased  with  the  throw  of  the  eccentric  and  that  for 
expansion  lessened.  This  is  shown  clearly  in  both  the  motion  diagrams 
and  the  table.  With  the  first  curve  and  a travel  of  2L  inches  the  steam  is 
cut  off  at  8 inches  for  the  backward  stroke  and  6f  inches  for  the  front, 
and  with  5 inch  travel  steam  is  admitted  during  20f  inches  of  the  back- 
ward and  2(H  inches  of  the  forward  stroke. 

Question  373.  How  is  the  point  of  release  or  exhaust  of  the  steam 
affected  by  the  link  ? 

Answer,  As  the  travel  increases,  it  is  delayed  until  later  in  the  stroke. 
Thus,  with  2-§-  inches  travel  the  steam  is  exhausted  or  released  from  the 
cylinder  during  the  backward  stroke  when  the  piston  has  moved  17  inches, 
and  on  the  return  stroke  at  16f  inches,  whereas,  with  5 inches  travel  of  the 
valve,  the  release  is  delayed  until  23£  inches  of  the  stroke.  An  examina- 
tion of  the  diagram  and  table  will  show  very  clearly  the  relation  of  the 
point  of  release  to  the  travel. 

QUESTION  374.  How  is  the  lead  affected  by  the  ordinary  link-motion  ? 

Answer.  It  is  increased  as  the  travel  is  diminished,  as  is  shown  in  the 
table,  and  also  by  the  inclination  of  the  curves  at  the  top  and  bottom  of 
the  diagram. 


The  Valve  Gear. 


3l5 


QUESTION  375.  What  is  the  cause  of  this  change  of  the  amount  of 
lead? 

Answer.  This  can  be  best  explained  by  reference  to  fig.  276,  which 
represents  a link  with  very  short  eccentric- rods.  If  the  centre  from  which 
the  link  was  drawn  was  in  the  centre  of  the  axle,  S,  and  the  eccentric 
straps  embraced  the  axle  instead  of  the  eccentrics,  their  ends,  m and  n, 
from  S as  a centre,  would  each  describe  the  same  arc,  a b c,  parallel  with 
the  centre  line,  x y,  of  the  link,  and  the  latter  could  then  obviously  be 
raised  and  lowered  without  moving  the  block,  b,  or  rocker-pin,  f,  at  all. 
But  the  eccentric  straps  being  attached  to  the  eccentrics,  as  shown  by  the 
dotted  lines,  when  the  rods  are  raised  or  lowered  they  describe  arcs,  e f 
and  f g,  from  the  centres,  s and  i,  of  the  eccentrics,  and  not  from  the 
centre  of  the  axle.  When  the  link  is  lowered,  then  the  end,  in,  of  the 
upper  rod  obviously  moves  in  the  arc,  in  f,  and  the  top  of  the  link  is 
moved  toward  the  axle,  a distance  equal  to  b f,  as  shown  in  fig.  277,  equal 
to  the  interval  between  the  arc,  a b c,  drawn  from  the  centre  of  the  axle, 
and  a f,  which  the  rod,  in  s,  describes  from  the  centre  of  its  eccentric. 
When  the  link  is  raised  from  mid-gear,  fig.  276,  to  back-gear,  a similar 
action  takes  place,  as  the  end,  n,  of  the  lower  rod  then  describes  an  arc,  n 
f,  so  that  the  whole  link  is  again  thrown  toward  the  axle  a distance,  b f 
equal  to  the  space  between  the  arcs  described  from  the  centre  of  the  axle 
and  the  centres  of  the  eccentrics.  When  the  position  of  the  eccentrics  is 
reversed,  as  shown  in  fig.  278,  the  link  is  moved  from  the  axle,  thus  caus- 
ing an  increase  of  lead  on  the  opposite  side  of  the  valve.  We  have  em- 
ployed for  our  illustrations  very  short  eccentric  rods,  in  order  to  make 
this  action  apparent  by  exaggerating  it.  It  is  obvious  from  the  engravings 
that  the  difference  in  the  lead  is  increased  as  the  eccentric  rods  are  short- 
ened, and  also  as  the  distance  between  the  points  of  connection  of  the 
rods  with  the  link  is  increased.  It  will  also  be  plain  that  increasing  the 
throw  of  the  eccentrics — that  is,  increasing  the  distance  of  the  centres,  s l, 
of  the  eccentrics  from  the  centre,  S,  of  the  axle  will  also  increase  the 
variation  in  the  lead  in  full  and  mid-gear. 

Question  376.  What  is  meant  by  the  distribution  of  steam  in  the 
cylinder  ? 

Answer.  It  means  the  admission  and  exhaust  of  steam  to  and  from 
the  cylinder  in  relation  to  the  stroke  of  the  piston  or  the  revolution  of  the 
crank. 

Question  377.  What  are  the  principal  periods  or  elements  of  the  dis- 
tribution of  steam  by  the  slide-valve  and  link-motion  ? 


The  Valve  Gear. 


317 


Answer.  They  are : 

1.  The.  pre-admission  due  to  the  lead — that  is,  the  admission  of  steam 
into  the  cylinders  in  front  of  the  piston  before  it  reaches  the  end  of  its 
stroke. 

2.  The  admission  of  steam  after  the  piston  has  commenced  its  stroke. 

3.  The  expansion  of  steam  in  the  cylinder. 

4.  The  pre-release  or  exhaust  of  steam  before  the  piston  has  completed 
its  stroke. 

5.  The  release  or  exhaust  during  the  return  stroke  of  the  piston. 

6.  The  compression  of  steam  or  closing  the  exhaust  before  the  piston 
has  completed  its  return  stroke. 

QUESTION  378.  What  is  meant  by  the  clearance  of  the  piston  ? 

Answer.  As  explained  in  answer  to  Question  122,  it  is  the  space 
between  the  piston  and  the  cylinder-head  when  the  former  is  at  the  end 
of  its  stroke.  If  the  piston  touched  the  cylinder-head  at  the  end  of  each 
stroke,  it  would  cause  a concussion  or  “ thump,’'  which  would  injure  these 
parts.  Owing  to  the  impossibility  of  constructing  machinery  with  abso- 
lute accuracy,  it  is  therefore  necessary  to  leave  a space,  usually  from  ^toj 
inch  wide,  between  the  piston  and  the  cylinder-heads,  so  as  to  be  certain 
that  they  will  not  strike  each  other  should  there  be  any  slight  inaccuracies 
in  the  length  of  the  piston-rods,  connecting-rods,  frames,  or  other  parts. 

QUESTION  379.  Why  is  it  desirable  to  open  the  steam-port  and  admit 
steam  at  the  end  of  the  cylinder  toward  which  the  piston  is  moving  BE- 
FORE the  latter  has  completed  its  stroke  ? 

Answer.  Because  it  is  essential,  in  order  to  insure  a good  action  of  the 
steam,  that  the  maximum  cylinder  pressure  should  be  attained  at  the  very 
commencement  of  the  stroke.  If  the  steam-port  was  not  opened  until 
after  the  piston  had  commenced  its  stroke,  some  appreciable  time  would 
be  consumed  in  filling  the  clearance  space  and  the  steam-way  with  steam. 
It  is  also  found,  especially  if  an  engine  is  working  at  a high  speed,  that  a 
slide-valve  worked  by  the  ordinary  link-motion  will  not  open  the  steam- 
port  rapidly  enough  to  enable  steam  of  the  maximum  boiler  pressure  to 
fill  the  space  after  the  receding  piston,  unless  the  valve  begins  to  open  the 
port  before  the  piston  reaches  the  end  of  the  stroke. 

Another  advantage  resulting  from  the  pre-admission  of  steam  consists 
in  the  smooth  working  of  the  engine  at  high  speeds,  a circumstance  which 
reduces  greatly  the  wear  and  tear  of  the  working  gear.  As  the  piston 
approaches  the  end  of  its  stroke,  the  pre-admitted  steam  forms  a kind  of 
elastic  cushion,  which  is  well  calculated  to  absorb  the  momentum  of  the 


318 


Catechism  of  the  Locomotive. 


reciprocating  parts  at  that  instant.  The  pressure  due  to  the  momentum 
of  these  parts  will,  of  course,  depend  upon  their  weight  and  the  speed  of 
working,  increasing  directly  as  the  square  of  the  speed.  It  follows  from 
this  that  the  lead  should  increase  with  the  speed,  and  that  it  should  be 
greatest  at  high  speeds.  As  has  been  shown  before,  this  condition  is  fully 
accomplished  by  the  ordinary  shifting-link  motion. 

Question  380.  Upon  what  does  the  admission  of  steam  into  the  cylinder 
depend? 

Answer.  It  depends  in  the  first  place  upon  the  opening  of  the  throttle- 
valve,  and  the  size  of  the  pipes  and  passages  through  which  it  is  conveyed 
from  the  boiler  to  the  cylinder.  In  the  second  place,  it  depends  upon  the 
time  and  amount  of  opening  of  the  steam-port  by  the  valve. 

Question  381.  What  should  be  the  pressure  of  the  steam  in  the  cylinder 
during  admission  ? 

Answer.  In  order  that  the  steam  may  be  used  to  most  advantage,  it 
should  be  admitted  and  maintained  in  the  cylinder  as  near  full  boiler 
pressure  as  possible  during  the  whole  period  of  admission.  If  the  opening 
of  either  the  throttle-valve  or  the  steam-ports  is  not  sufficient  to  allow  the 
steam  to  flow  into  the  cylinder  at  full  boiler  pressure,  the  steam  is  said  to 
be  wire-drawn,  and  some  of  the  advantage  of  using  it  expansively  is  then 
lost. 

QUESTION  382.  Why  is  it  difficult  to  admit  and  maintain  steam  at  the 
full  boiler  pressure  in  the  cylinder  during  admission  ? 

Answer.  Because  with  the  link  motion  the  travel  of  the  slide-valve 
must  be  reduced  in  order  to  cut  off  the  steam  “short,”  or  soon  after  the 
beginning  of  the  stroke  of  the  piston.  When  the  travel  is  reduced,  the 
valve  opens  the  port  only  a small  distance,  so  that  the  area  of  the  opening 
is  not  then  sufficient  to  allow  the  steam  to  flow  into  the  cylinder  with 
sufficient  rapidity  to  fill  it  at  full  boiler  pressure,  especially  if  the  engine  is 
working  at  a high  speed.  Thus,  by  referring  to  the  table  given  on  page 
313,  and  to  the  motion-curves  in  fig.  275,  it  will  be  seen  that  when  the 
steam  is  cut  off  at  from  £ to  \ stroke,  the  port  is  opened  for  the  admission 
of  steam  only  from  L to  i inch  wide.  From  the  curves  it  will  also  be  seen 
that  the  valve  then  acquires  its  maximum  travel,  and  the  steam-port  its 
greatest  width  of  opening  very  soon  after  the  piston  begins  its  stroke ; 
after  which  the  port  is  gradually  closed,  so  that  before  the  steam  is  en- 
tirely cut  off  the  opening  is  so  much  reduced  in  area  that  the  steam  can- 
not flow  through  it  rapidly  enough  to  maintain  the  steam  at  full  boiler 
pressure  in  the  cylinder  when  the  engine  is  working  at  high  speeds. 


The  Valve  Gear. 


319 


QUESTION  383.  What  means  are  used  to  overcome  this  difficulty  and 
thus  admit  steam  at  f idler  boiler  pressure  when  the  valve  is  cutting  off 
short ? 

Answer . In  the  first  place,  the  steam-ports  are  made  from  ten  to 
twelve  times  as  long  as  they  are  wide,  so  that  a narrow  opening  will  have 


Fig.  279. 


a comparatively  large  area.  In  the  second  place,  by  giving  the  valve  lead, 
not  only  are  the  clearance  space  and  the  steam-way  filled  with  steam  when 
the  piston  begins  its  stroke,  but  the  port  is  then  open  a distance  equal 
to  the  lead.  With  the  ordinary  link-motion,  as  has  already  been  shown, 
this  lead  increases  as  the  travel  and  period  of  admission  diminish,  so  that 


320 


Catechism  of  the  Locomotive. 


the  smaller  the  total  distance  that  the  port  is  opened,  the  greater  is  its 
opening  at  the  beginning  of  the  stroke.  As  the  steam  is  usually  cut  off 
short  when  locomotives  run  at  high  speeds,  it  will  be  seen  that  the 
increased  lead  which  is  imparted  to  the  valve  by  the  shifting  link  is  an 
advantage  rather  than  a disadvantage.  But  while  it  is  often  possible  in 
this  way  to  secure  a pressure  of  steam  in  the  cylinder  at  the  beginning  of 
the  stroke  equal  or  nearly  so  to  that  in  the  boiler,  yet  it  is  almost  impossi- 
ble to  maintain  this  pressure  during  the  whole  period  of  admission,  when 
the  steam  is  cut  off  short  and  the  engine  working  at  a high  speed.  To 
obviate  this  evil  what  is  called  the  Allen  Valve  was  designed,  which  is 
represented  in  fig.  279.  This  valve  has  a channel  or  supplementary  port, 
a a,  which  passes  over  the  exhaust  cavity,  and  has  two  openings,  b b',  in 
the  valve-face.  When  the  valve  begins  to  admit  or  “ take  *'  steam,  at  f , as 
shown  in  fig.  280,  it  will  be  seen  that  it  also  uncovers  the  opening,  a a , at  e , 
and  thus  admits  steam,  at  e , which  passes  through  the  channel,  a a, 
and  enters  the  steam-port,  c,  at  b , and  in  this  way  there  is  a double  open- 
ing for  the  admission  of  steam.  The  opening,  b , of  the  supplementary 
port  is  closed  as  the  valve  advances,  but  when  this  takes  place  the  steam- 
port  is  uncovered  far  enough,  at  f,  to  admit  all  the  steam  that  is  required. 
This  form  of  valve  is  very  efficient  when  the  travel  and  point  of  cut-off  are 
very  short.  It  then  gives  just  twice  as  much  opening  as  the  ordinary 
valve  for  the  admission  of  steam. 

Question  384.  What  is  meant  by  the  pre-release  of  steam  ? 

Answer.  It  is  the  release  of  the  steam  before  the  piston  has  completed 
its  stroke.  If  the  steam  was  confined  in  the  cylinder  until  the  piston  had 
reached  the  end  of  its  stroke,  there  would  not  be  time,  nor  will  it  be  pos- 
sible, with  a slide-valve  and  link-motion,  to  secure  a sufficiently  large 
opening  of  the  port  to  permit  the  steam  to  escape  from  the  cylinder  before 
the  piston  begins  its  return  stroke.  If  there  were  no  pre-release,  there 
would  therefore  be  more  or  less  back  pressure  on  the  piston. 

Question  385.  Upon  what  does  the  amount  of  pre-release  depend? 

Answer.  First,  as  has  already  been  explained  in  answer  to  Question 
150,  on  the  amount  of  inside  lap ; and  second,  on  the  outside  lap  of  the 
valve  and  the  lead  of  the  eccentrics ; and  third,  on  the  travel  of  the  valve. 
The  less  the  inside  lap,  the  greater  the  outside  lap  and  consequent  lead  of 
the  eccentrics,  and  the  shorter  the  travel  of  the  valve,  the  earlier  will  be 
the  release.  The  proper  amount  of  this  pre-release  depends  upon  the 
velocity  of  the  piston  and  the  quantity  of  steam  to  be  discharged  or  the 
degree  of  expansion.  From  the  motion-curves,  in  fig.  275,  it  will  be  seen 


The  Valve  Gear. 


321 


that  it  is  a marked  feature  of  the  shifting-link  motion  that  the  pre-release 
occurs  earlier  in  the  stroke  as  the  link  approaches  mid-gear,  or  as  the 
travel  of  the  valve  diminishes.  As  the  link  is  usually  worked  near  that 
position  when  the  engine  is  run  at  a high  speed,  it  will  be  seen  that  in 
this  respect  again  the  link-motion  is  well  adapted  for  working  the  slide- 
valves  of  locomotives. 

Question  386.  What  governs  the  period  of  release  ? 

Answer.  The  release,  like  the  pre-release,  is  dependent  upon  the 
amount  of  inside  lap,  the  outside  lap  and  consequent  lead  of  the  eccen- 
trics, and  the  travel  of  the  valve.  The  addition  of  inside  lap  has  the 
effect  of  closing  the  port  earlier  than  it  would  be  closed  without,  and  thus 
shortening  the  period  of  release  and  also  of  reducing  the  area  of  the  open- 
ing of  the  port. 

With  the  same  travel,  increase  of  outside  lap  and  lead  shortens  the 
period  of  release,  but  has  no  effect  on  the  width  of  the  opening  of  the  port 
to  the  exhaust. 

Increase  of  travel,  with  the  same  outside  lap,  lengthens  the  period  of 
release  and  also  increases  the  width  of  the  opening  of  the  port  to  the 
exhaust. 

Question  387.  What  governs  the  period  of  compression? 

Answer.  As  compression  begins  when  release  ends,  or  when  the  port 
is  closed  to  the  exhaust,  it  is  controlled  by  exactly  the  same  causes,  and  as 
the  two  events  occur  simultaneously,  of  course  whatever  shortens  the 
period  of  release  lengthens  that  of  compression. 

Question  388.  What  effect  do  the  clearance  spaces  and  steam-ways 
have  upon  the  compression  of  the  confi7ied  steam  ? 

Answer.  By  referring  to  the  motion-curves,  in  fig.  275,  it  will  be  seen 
that  the  steam-port  is  closed  by  the  exhaust  edge  of  the  valve,  or  com- 
pression begins  some  time  before  the  piston  reaches  the  end  of  the  stroke. 
This  is  especially  the  case  when  the  travel  of  the  valve  is  reduced  and 
steam  is  cut  off  short.  The  result  is  that  the  remaining  portion  of  the 
cylinder,  through  which  the  piston  must  move  after  the  port  is  closed  to 
tne  exhaust,  is  filled  with  steam  of  atmospheric  pressure,  or  possibly  a lit- 
tle above  the  pressure.  As  this  is  confined  in  the  cylinder,  it  is  com- 
pressed by  the  advance  of  the  piston.  If  there  was  no  room  between  it 
and  the  cylinder  at  the  end  of  the  stroke,  then  either  the  cylinder  would 
be  burst  or  the  valve  would  lift  so  far  as  to  allow  the  compressed  steam  to 
flow  back  into  the  steam-chest.  The  clearance  and  the  steam  passages, 
however,  afford  considerable  room,  into  which  the  confined  steam  can  be 


322 


Catechism  of  the  Locomotive. 


compressed  without  danger  of  bursting  the  cylinder  or  of  raising  the  slide- 
valve  when  there  is  steam  in  the  steam-chest.  As  the  clearance  spaces 
and  steam-ways  must  be  filled  with  high-pressure  steam  at  the  beginning 
of  each  stroke,  it  must  be  obtained  either  by  taking  a supply  of  “live”* 
steam  from  the  steam-chest,  or  by  compressing  into  the  clearance  spaces 
the  low-pressure  steam  that  still  remained  in  the  cylinder  when  the  port 
was  closed  to  the  exhaust.  By  the  latter  process,  a certain  quantity  of 
steam  is  saved  at  the  expense  of  increased  back  pressure.  It  should  be 
borne  in  mind,  also,  that  the  total  heat  of  the  compressed  steam  increases 
with  its  pressure,  and  as  its  pressure  approaches  that  in  the  boiler,  its  tem- 
perature must  also  be  raised  from  that  due  to  about  atmospheric  pressure 
to  near  that  in  the  boiler.  These  changes  of  temperature  which  the  steam 
undergoes  will  affect  the  surface  of  the  metal  with  which  the  steam  is  in 
contact  during  the  period  of  compression  ; it  follows  from  this,  that  the 
ends  of  the  cylinder  principally  comprising  the  clearance  spaces  must  ac- 
quire a higher  temperature  than  those  parts  where  expansion  only  takes 
place.  This  is  an  important  consideration,  since  the  fresh  steam  from  the 
boiler  comes  first  in  contact  with  these  spaces,  and  by  touching  surfaces 
which  have  thus  previously  been  heated,  as  it  were,  by  the  high  tempera- 
ture of  the  compressed  steam,  less  heat  will  be  abstracted  from  the  fresh 
steam,  and  therefore  a less  amount  of  water  will  be  deposited  in  the 
cylinder,  f 

It  will  thus  be  seen  that  the  effect  of  compression  is  to  fill  the  clearance 
spaces  and  steam-ways  with  compressed  steam  before  pre-admission  be- 
gins. As  already  stated,  this  is  done  at  the  expense  of  back  pressure  in 
the  cylinder.  It  must  be  remembered  that  all  the  energy,  excepting  that 
part  which  is  wasted  by  loss  of  heat,  friction,  etc.,  which  is  consumed  in 
compressing  the  confined  steam,  is  again  given  out  to  the  piston  by  ex- 
pansion. The  confined  steam  also  acts  as  an  elastic  cushion  to  receive 
the  piston,  just  as  the  steam  which  is  admitted  before  the  end  of  the 
stroke  would  if  there  was  no  compression.  Compression,  therefore,  has 
the  effect  of  saving  the  quantity  of  live  steam  which  it  would  otherwise 
be  necessary  to  admit  before  the  end  of  the  stroke  to  fill  the  clearance 
spaces  and  steam-ways,  and  also  to  “ cushion  ” the  piston.  As  the  momen- 
tum of  the  piston  and  other  parts  depend  upon  their  weight  and  the 
speed  at  which  they  are  working,  increasing  directly  as  the  square  of  the 

* The  term  “ live”  steam  means  steam  taken  direct  from  the  boiler  and  which  has  not  been 
used  in  the  cylinder  or  to  do  any  work. 

t Bauschinger’s  Indicator  Experiments  on  Locomotives. 


The  Valve  Gear. 


323 


speed,  from  which  it  follows  that  the  compression  should  increase  rapidly 
with  the  speed  and  should  be  the  greatest  at  high  speeds.  As  the  ports 
are  prematurely  closed  to  the  exhaust  with  the  shifting-link  motion,  and 
as  the  lead  increases  rapidly  as  the  link  approaches  mid-gear,  and  the 
amount  of  compression  is  at  the  same  time  correspondingly  augmented,  it 
will  be  seen  that  the  shifting-link  motion  fulfils  these  conditions  very 
perfectly. 

The  pressure  to  which  the  confined  steam  will  rise  depends,  of  course, 
upon  the  amount  of  the  period  of  compression,  and  also  on  the  size  of  the 
clearance  spaces.  As  it  is  possible  to  have  such  an  amount  of  compres- 
sion that  it  will  exceed  the  boiler  pressure,  and  thus  raise  the  valve  from 
its  seat  and  be  forced  back  into  the  steam-chest,  some  care  must  be  exer- 
cised to  proportion  the  one  to  the  other,  so  that  the  degree  of  the  con- 
fined steam  may  not  be  excessive. 

Question  389.  How  can  the  effect  of  the  distribution  of  the  steam 
upon  its  action  in  the  cylinder  be  determined  by  experiment  ? 

Answer.  As  already  explained  in  answer  to  Question  108,  this  can  be 
done  by  an  instrument  called  a steam-indicator. 

Question  390.  What  is  the  construction  of  this  instrument? 

Answer.  Fig.  281  represents  the  Tabor  Indicator.*  It  consists  of  a 
cylinder,  B (which  is  shown  in  section),  into  which  a piston,  A,  is  accu- 
rately fitted,  but  so  that  it  will  move  freely  in  the  cylinder.  The  piston- 
rod,  C,  is  surrounded  with  a spiral  spring,  D,  the  lower  end  of  which  is 
attached  to  the  top  of  the  piston,  and  the  upper  end  to  the  cylinder  cover. 
When  steam  is  introduced  below  the  piston  it  pushes  it  up  in  the  cyl- 
inder and  the  spring  is  compressed.  If  there  should  be  a vacuum  below 
the  piston,  the  air  above  it  will  press  the  piston  downward  and  extend  the 
spring.  This  latter  occurs  only  when  the  indicator  is  used  on  condensing 
engines.  Of  course  the  distance  which  the  piston  is  forced  up  by  the 
steam-pressure  below  it  depends  upon  the  amount  of  pressure,  and  also 
on  the  tension  of  the  spring ; and  therefore  if  a pencil  was  attached  to  the 
piston-rod  so  that  it  could  mark  on  a moving  card  in  front  of  it,  a diagram 
would  be  drawn,  which  would  indicate  the  steam-pressure,  as  was  ex- 
plained in  answer  to  Question  108.  But  there  are  some  practical  difficul- 
ties in  the  way  of  doing  this.  It  is  found  that  if  the  pencil  is  attached 
directly  to  the  piston-rod  of  the  indicator,  the  distance  through  which 
they  must  move  in  order  to  make  the  scale  of  the  diagram  sufficiently 
large  to  be  clear,  is  so  great  that  the  momentum  of  the  parts  carries  them 


* Manufactured  by  the  Ashcroft  Manufacturing  Company,  111  Liberty  Street,  New  York. 


324 


Catechism  of  the  Locomotive. 


farther  than  the  pressure  of  the  steam  alone  would  move  them.  The  dis- 
tance through  which  the  piston  would  move,  moreover,  makes  it  difficult 
to  indicate  the  changes  of  pressure  simultaneously  with  the  position  of 
the  piston,  as  the  latter  must  travel  while  the  action  is  taking  place,  and 
thus  the  diagram  shows  changes  of  pressure  later  or  more  gradually  than 
they  occur.*  To  overcome  these  and  other  difficulties,  the  piston-rod  of 


Fig.  281.  Tabor  Indicator. 


the  indicator  which  we  have  illustrated  is  attached  by  a link,  E,  to  the 
lever,  F G,  which  carries  a pencil,  G,  on  its  outer  end.  By  this  means  the 
piston  has  only  one-fourth  of  the  motion  that  it  imparts  to  the  pencil, 
so  that  the  momentum  of  the  moving  parts  is  comparatively  slight. 

In  order  that  the  pencil  may  draw  a straight  line,  instead  of  a curved 
one,  a roller  is  attached  to  the  lever  at  7/.  This  moves  in  a curved  slot, 
HI,  which  causes  the  end,  G,  to  move  in  a straight  line  instead  of  the  arc 

* Richard’s  Steam  Indicator,  by  Charles  T.  Porter. 


The  Valve  Gear. 


825 


of  a circle.  The  levers  and  all  the  parts,  are  all  made  as  light  as  possible, 
so  that  their  weight  will  have  little  effect  on  the  motion  of  the  indicator 
piston. 

The  paper  or  card,  P,  on  which  the  diagram  is  drawn,  is  wrapped 
around  a brass  cylinder,  K K.  This  cylinder  is  made  to  revolve  part  of 
the  way  around  by  a strong  twine,  L M,  which  is  wrapped  around  a pully, 
N,  at  the  bottom  of  the  cylinder.  The  twine  is  attached  to  a lever,  simi- 


Fig.  282.  Crosby  Indicator. 


lar  to  that  shown  in  fig.  38,  which  receives  a reciprocating  motion  from 
the  piston  of  the  engine.  The  twine  can,  of  course,  move  the  cylinder  in 
only  one  direction,  and  therefore  a coiled  spring  similar  to  a clock  spring 
is  placed  inside  of  the  cylinder  to  draw  it  back  when  the  twine  is  relaxed. 
In  this  way  the  paper  cylinder  or  drum  receives  a part  of  a revolution  at 
each  stroke  of  the  piston  and  moves  simultaneously  with  it.  This  drum 


326 


Catechism  of  the  Locomotive. 


is  used  instead  of  a flat  qard,  shown  in  fig.  52.  The  motion  of  the  paper 
on  this  drum  will,  however,  be  exactly  the  same  in  relation  to  the  pencil 
as  the  motion  of  a flat  card  would  be. 

Fig.  282  is  an  outside  view,  and  fig.  283  a section  of  the  Crosby*  Indi- 


Fig.  283.  Crosby  Indicator. 

cator,  which  is  similar  to  the  one  just  described,  excepting  the  mechanism 
for  producing  a rectillinear  motion  of  the  pencil,  which  differs  somewhat 
from  the  other,  as  is  shown  in  the  engravings. 

The  method  of  attaching  an  indicator  to  a locomotive  is  represented  in 
fig.  284.  It  will  be  seen  from  this  that  it  is  placed  over  the  middle  of  the 
steam-chest  and  is  connected  to  each  end  of  the  cylinder  with  f . inch 
pipes.  A three-way  cock  is  placed  at  the  point,  A,  where  the  horizontal 


* Manufactured  by  the  Crosby  Steam  Gauge  & Valve  Company,  of  Boston. 


The  Valve  Gear. 


82’ 


pipe  connects  with  the  vertical  one  leading  to  the  indicator,  by  which 
steam  can  be  entirely  shut  off  from  the  indicator,  or  communication  can 
be  established  with  either  end  of  the  cylinder.  The  arrangement  of  the 
levers  for  giving  motion  to  the  indicator  drum  and  that  of  the  seat,  which 
is  very  requisite  for  the  experimenter,  will  be  readily  understood  from  the 
engraving  without  further  explanation.  It  is  thought  by  some  engineers 
that  the  indicator  should  be  applied  as  near  to  each  end  of  the  cylinder 


Fig.  284.  Method  of  Applying  Indicator. 


as  possible.  It  is  believed,  though,  that  if  the  pipes,  cocks,  and  their 
connections,  are  made  large  enough  so  as  not  to  impede  the  motion  of 
the  steam,  no  appreciable  error  will  arise  from  the  method  illustrated  in 
fig.  284. 

QUESTION  391.  What  is  the  form  of  an  indicator  diagram ? 


328 


Catechism  of  the  Locomotive. 


Answer.  This  depends  upon  the  pressure  of  the  steam,  the  action  and 
proportions  of  the  valve,  the  speed  of  the  engine,  and  a variety  of  other 
circumstances.  To  show  the  influence  of  the  action  of  the  valve,  it  will 


Indicator  Diagrams. 

be  supposed  that  an  indicator  diagram  is  taken  with  a valve  like  that 
shown  in  fig.  67,  and  that  its  movement  is  represented  by  the  two  motion- 
curves  shown  by  heavy  lines  in  fig.  266. 

It  should  be  explained,  first,  that  with  ordinary  indicators  the  size  of 


The  Valve  Gear. 


329 


the  diagrams  is  from  3 to  4 inches  long  and  If  to  2 inches  wide.  There- 
fore, the  springs  which  resist  the  steam  pressure  under  the  indicator  pis- 
ton, are  made  of  varying  degrees  of  tension,  which  are  designated  as  Nos. 
4,  8,  12,  16,  20,  30,  40,  50,  60,  80,  100.  The  number  of  the  spring  repre- 
sents the  pressure  in  pounds  per  square  inch  required  to  compress  it 
sufficiently  to  move  the  pencil  vertically  1 inch  on  the  diagram.  There- 
fore, by  dividing  the  boiler  pressure  in  pounds  by  the  desired  height  of 
diagram  in  inches,  the  result  will  be  the  number  of  the  spring  required.  A 
boiler  pressure  of  140  lbs.  per  square  inch  will  be  assumed,  so  that  if  the 
diagram  is  not  to  exceed  If  inches  in  height,  a number  80  spring  should 
be  used. 

Fig.  285  is  supposed  to  represent  an  indicator  diagram  which  would  be 
made  by  the  valve,  shown  in  fig.  266,  when  its  movement  is  as  represented 
by  the  heavy  motion-curve.  The  horizontal  line,  m n,  fig.  285,  represents  the 
atmospheric  line  which  would  be  drawn  by  the  pencil  of  the  indicator  if 
the  card  was  moved  horizontally  when  there  is  no  steam  on  the  indicator, 
but  only  atmospheric  pressure  above  and  below  its  piston.  The  pencil  is 
supposed  to  stand  at  G,  at  the  beginning  of  the  backward  stroke  of  the 
piston.  As  the  valve  has  inch  lead  it  opens  the  steam-port  a little 
before  the  piston  reaches  the  end  of  the  stroke.  While  the  crank  is  mov- 
ing past  the  dead-point  the  valve  has  considerable  movement,  so  that  if 
the  engine  is  moving  slowly,  steam  of  full  boiler  pressure  "will  be  admitted 
into  the  cylinder,  and  the  piston  of  the  indicator  will  be  forced  upward, 
and  the  pencil  will  draw  the  line,  G A , which  is  called  the  “ ad?nission 
line.”  At  the  beginning  of  the  stroke  the  valve  opens  the  port  quickly, 
and  it  remains  open  until  the  piston  has  reached  21f  inches,  of  its  stroke, 
and  during  that  period  the  pencil  draws  the  horizontal  line,  A B , which  is 
called  the  “steam  line.”  When  the  pencil  gets  to  B,  the  steam-port  is 
closed  and  the  steam  is  cut  off  or  confined  in  the  cylinder  and  then  ex- 
pands, and  the  pencil  draws  the  line,  B C,  which  is  called  the  “ expansion 
curve.”  B is  therefore  called  “ the  point  of  cut-off .”  When  the  pencil 
reaches  C,  the  exhaust-port  is  opened  and  the  steam  escapes,  so  that  the 
pressure  is  rapidly  reduced,  and  the  spring  above  the  indicator-piston 
forces  it  down  and  the  pencil  draws  the  line,  C D E.  C is  called  the 
“ point  of  release,”  and  C D E the  “ exhaust  line.” 

During  the  return  stroke  of  the  piston,  not  all  the  steam  escapes  from 
the  cylinder,  and,  especially  if  the  speed  is  rapid,  there  is  more  or  less 
“ b'ack pressure,”  as  it  is  called,  in  front  of  the  piston  which  causes  the 
pencil  to  draw  a line,  E F,  called  the  “ back-pressure  line,”  somewhat 


330 


Catechism  of  the  Locomotive. 


above  the  atmospheric  line,  m n.  Before  the  piston  reaches  the  end  of  its 
return  stroke  the  port  is  closed  to  the  exhaust,  and  the  steam  and  air 
enclosed  in  the  cylinder  is  compressed  by  the  advancing  piston,  so  that 


Fig.  287. 


Indicator  Diagrams. 


the  indicator  pencil  draws  the  line,  F G,  called  the  “ compression  curve." 
The  point,  F,  is  called  the  “ point  of  compression or  “ point  of  exhaust 
closure ” 


The  Valve  Gear. 


331 


Fig.  286  represents  the  form  of  diagram  which  would  be  made  by  the 
valve,  if  its  movement  was  as  represented  by  the  smaller  motion-curve 
drawn  in  light  lines  in  fig.  266.  It  will  be  seen  that  steam  is  cut  off  at  16 
inches  instead  of  21^-  inches.  Release  occurs  at  21  inches,  and  compres- 
sion begins  at  a point  2 inches  from  the  end  of  the  stroke. 

Fig.  287  is  such  a diagram  as  would  be  made  when  steam  is  cut  off  at  8 
inches,  and  in  fig.  288  expansion  begins  at  4^  inches.  In  order  to  make 
these  diagrams  clear  a scale  of  the  indicator  spring  is  drawn  on  the  left 
side  of  the  engraving,  and  the  horizontal  lines  on  the  diagram  represent 
the  steam-pressure,  and  the  vertical  lines  indicate  inches  of  the  stroke  of 
the  piston. 


St 

H? 


Sh- 

ot 

0.0 


0 1 2 3 1 5 6 7 8 9 10  11  12  13  14  15  16  17  18  19  20  21  22  23  24 


Question  392.  What  should  be  the  form  of  an  indicator  diagram , if 
the  steam  is  distributed  by  a link-motion  so  as  to  produce  the  best  practicable 
action  in  the  cylinders  ? 

Answer.  It  should  approximate  to  that  shown  in  fig.  289.  The  atmos- 
pheric and  vacuum  lines,  m n and  op,  are  indicated,  as  already  explained. 
The  points  at  which  the  different  periods  of  the  distribution  begin  are 
indicated  by  small  circles,  and  the  letters,  A B C D E F G and  H. 


332 


Catechism  of  the  Locomotive. 


The  diagram  represents  a distribution  of  steam  produced  by  a valve 
having  £ inch  outside  and  inside  lap.  The  eccentrics  have  5 inches 
throw,  and  the  steam-ports  are  1£  and  the  exhaust  2f  inches  wide.  The 
valve  is  cutting  off  at  8 inches,  or  one-third  of  the  stroke.  Pre-admission 
begins  at  G,  when  the  piston  still  has  1 inch  to  move  before  reaching  the 
end  of  its  stroke.  Admission,  of  course,  begins  at  A with  the  stroke, 
expansion  at  B or  8 inches,  release  or  exhaust  at  C,  17  inches,  and  com- 
pression at  F,  16  inches  of  the  return  stroke.  The  valve  is  supposed  to 
be  set  with  tV  inch  lead  at  full  stroke.  When  the  steam  is  cut  off  at  8 
inches  of  the  stroke,  the  valve  has  2f  inches  travel  and  l inch  lead.  The 
steam-pressure  in  the  boiler  is  supposed  to  be  140  lbs.  above  the  atmos- 
phere. Of  course  when  the  valve  cuts  off  at  different  points  of  the  stroke, 
the  periods  of  distribution  will  be  somewhat  changed ; but  from  the  above 
diagram  the  principal  features  of  a good  distribution  can  be  explained. 

These  are  : First  that  the  steam-pressure  should  rise  rapidly  during  the 
period  of  pre-admission,  so  that  there  will  be  nearly  full  boiler  pressure  in 
the  cylinder  at  the  beginning  of  the  stroke.  When  this  occurs,  the  pre- 
admission line  will  rise  from  G,  to  such  a point  as  will  indicate  nearly  or 
quite  full  boiler  pressure  in  the  cylinder.  The  same  pressure  should  then 
be  maintained  in  the  cylinder  during  the  whole  period  of  admission,  and 
the  admission  line  from  A to  £ should  therefore  approximate  to  a straight 
horizontal  line.  When  expansion  begins,  the  pressure  will  fall.  The  ex- 
pansion line  should  approximate  to  a hyperbolic  curve,  but  in  laying  out 
this  curve  allowance  must  be  made  for  the  clearance  space  between  the 
piston  and  cylinder  heads  and  the  contents  of  the  steam-ways.  The  cubi- 
cal contents  of  these  at  each  end  of  the  cylinders  of  locomotives  are  usu- 
ally from  5 to  10  per  cent,  of  the  space  swept  through  by  the  piston.  It 
will  be  assumed  that  this  is  equal  to  the  space  swept  by  the  piston  in 
moving  2 inches.  A line,  I J,  is  therefore  drawn,  2 inches  from  A O, 
which  represents  the  front  end  of  the  cylinder,  and  the  space,/ JO  A,  will 
represent  the  clearance.  When  the  piston  has  moved  8 inches,  then  the 
steam  in  the  cylinder,  instead  of  filling  only  the  space  through  which  the 
piston  has  moved,  which  is  represented  by  A O K B,  also  fills  the  clear- 
ance space  and  is  represented  by  I J KB.  Therefore,  in  laying  out  the 
expansion  curve,  B C r.  we  must  calculate  for  the  expansion  of  a quantity 
of  steam  sufficient  to  fill  the  cylinder  in  front  of  the  piston  and  the  clear- 
ance spaces,  and  which  is  represented  by  the  area,  I J K B.  If  there  is 
much  loss  of  heat  by  radiation  or  other  causes,  the  diagram  will  fall  con- 
siderably below  the  theoretical  curve.  With  cylinders  well  protected  and 


The  Valve  Gear. 


333 


with  dry  steam,  the  expansion  line  will  fall  slightly  below  a hyperbolic 
curve  at  the  beginning  of  the  period  of  expansion,  and  rise  above  it  dur- 
ing the  latter  part  of  the  same  period.  The  reason  of  this  is  that  the 
cylinder  is  heated  by  the  admission  of  live  steam  of  comparatively  high 
temperature,  so  that  when  the  pressure  becomes  reduced  by  expansion,  a 
part  of  the  water  which  is  condensed  in  the  cylinder  will  be  re-evaporated 
by  the  heat  in  the  latter.  From  the  point  of  the  release  or  exhaust,  C,  to 
the  end  of  the  stroke,  D,  the  exhaust  line  should  fall  rapidly,  so  that  there 
will  be  no  pressure  behind  the  piston  during  its  return  stroke.  To  explain 
the  theoretical  form  of  the  exhaust  line  would  lead  into  a very  abstruse 
discussion,  which  would  be  out  of  place  here.  It  will  be  sufficient  for  our 
purpose  to  call  attention  to  the  fact  that  the  pre-release  should  allow  as 
much  of  the  steam  in  the  cylinder  to  escape  as  is  possible  before  the  piston 
reaches  the  end  of  the  stroke,  so  that  the  back  pressure  during  the  return 


Fig.  290.  Indicator  Diagram. 


stroke  may  be  low.  It  is,  however,  only  at  comparatively  slow  speeds  that 
the  steam  in  locomotive,  cylinders  escapes  during  the  period  of  pre-release, 
so  that  the  back  pressure  is  reduced  to  that  of  the  atmosphere.  It  is 
essential  in  locomotives,  as  has  already  been  explained,  to  contract  the 
area  of  the  blast  orifices  or  exhaust  nozzles,  more  or  less  in  order  to  stimu- 
late the  draft  through  the  fire,  so  that  the  steam  cannot  escape  with  suffi- 
cient rapidity  to  reduce  the  back  pressure  to  that  of  the  atmosphere  if  the 


334 


Catechism  of  the  Locomotive. 


engine  is  running  fast.  Of  course  every  pound  of  back  pressure  on  the 
piston  is  equivalent  to  an  equal  amount  deducted  from  the  effective  pres- 
sure on  the  other  side. 

QUESTION  393.  How  can  the  net  effective  pressure  on  the  piston  be  shown 
by  indicator  diagrams  ? 

Answer.  This  can  be  done  by  taking  two  indicator  diagrams  on  the 
same  card  from  opposite  ends  of  the  cylinder,  as  shown  in  fig.  290.  The 
area,  A B C D P O and  A'  B'  C'  D'  O P,  represent  the  absolute  pressures 
ahead  of  the  piston  during  the  backward  and  forward  strokes.  The  areas, 
H G F E D P O and  H'  G'  F'  E’  D'  O P,  represent  the  absolute  pressures 
on  the  opposite  side  of  the  piston  or  the  back  pressure.  As  the  one  must 
be  deducted  from  the  other  to  get  the  net  pressure,  we  have  A B C 2 E’ 


E D'  H and  A'  B’  C'  1 F E D H',  as  the  areas  which  represent  the  net 
forward  pressure  on  the  piston.  At  each  end  of  the  stroke  the  back  pres- 
sure exceeds  the  forward  pressure,  and  therefore  we  have  the  two  areas, 
HID'  and  H'  2 D,  shaded  black,  which  represent  the  retarding  effect  on 
the  piston  at  each  end  of  the  stroke.  The  length  of  the  vertical  lines 
between  the  curves,  ABC  2 and  D’  E F'  2,  will  give  the  effective  pres- 
sure, and  similar  measures  on  the  black  areas  will  give  the  retarding 


The  Valve  Gear. 


335 


pressures  for  any  point  of  the  stroke.  This  will  be  made  still  clearer  if  we 
take  a line,  H D,  fig.  291,  as  the  line  of  no  pressure  on  the  piston  and  then 
lay  off  vertical  lines  equal  in  length  to  those  between  the  curves,  ABC  2 
and  D'  E’  F'  2,  of  fig.  290,  and  draw  a curve,  A B C w,  fig.  291,  through 
their  extremities.  This  curve  will  represent  the  net  pressure  on  the  piston, 
and  by  laying  off  vertical  lines  below  H D,  equal  in  length  to  those  in 
the  area,  H'  D 2,  and  drawing,  w H\  through  their  extremities,  this 
curve  and  the  area,  w H'  D , colored  black,  will  represent  the  net  back 
pressure  on  the  piston. 

In  studying  the  distribution  of  steam  and  designing  valve-gear,  every 
effort  should  be  made  to  reduce  the  back  pressure,  excepting  at  the  end 
of  the  stroke,  as  much  as  possible,  and  yet  maintain  a sufficient  supply  of 
steam,  and  therefore  the  line  of  back  pressure  should  conform  as  closely 
as  possible  to  the  atmospheric  line.  The  compression  line  should  approxi- 
mate to  a hyperbolic  curve,  beginning  with  the  period  of  compression. 
In  calculating  expansion,  allowance  must  be  made  for  the  clearance  space 
and  steam-ways  as  has  already  been  explained.  The  same  thing  is  true 
of  the  compression.  This  occurs  in  the  above  example  when  the  piston 
has  8 inches  or  more  to  move  before  completing  its  stroke.  There  is, 
therefore,  a quantity  of  steam  in  front  of  it  sufficient  to  fill  a cylinder  10 
inches  long.  This  steam  is,  of  course,  compressed  by  the  advance  of  the 
piston,  and  if  its  absolute  pressure  when  compression  begins  is  the  same 
as  that  of  the  atmosphere,  or  15  lbs.,  then  it  will  be  18.75  lbs.,  when  the 
piston  has  only  6 inches  to  move,  and  25  and  37.5  lbs.  absolute  pressure 
when  the  piston  has  4 and  2 inches  to  move,  and  when  the  pre-admission 
begins,  the  pressure  will  have  risen  to  75  lbs.  If  the  back  pressure  is 
above  that  of  the  atmosphere,  of  course  the  compression  will  be  corres- 
pondingly increased.  It  will  also  be  seen  that,  without  any  or  with  very 
little  clearance  space,  the  compression  would  at  the  end  of  each  stroke 
rise  above  the  boiler  pressure.  It  being  a peculiarity  of  the  ordinary 
shifting-link  motion  that  as  the  period  of  admission  is  reduced  that  of 
compression  is  lengthened,  the  latter  becomes  very  great  when  the  steam 
is  cut  off  at  less  than  one-third  or  one-fourth  of  the  stroke. 

QUESTION  394.  In  what  respect  would  a diagra7n  made  by  an  indicator 
differ  from  a theoretical form  represented  in  fig.  28q? 

Answer.  It  would  be  drawn  with  less  exactness — that  is,  the  corners  in- 
stead of  being  sharply  defined,  as  in  fig.  289,  would  be  more  or  less 
rounded,  as  shown  in  figs.  285  to  288,  and  the  curves  and  lines  would  vary 
somewhat  from  the  exact  mathematical  form  indicated  in  fig.  289.  The 


336 


Catechism  of  the  Locomotive. 


higher  the  speed  at  which  the  engine  is  working  when  the  diagrams  are 
taken,  the  greater  will  be  the  variation  from  the  theoretical  form. 

QUESTION  395.  If  the  amount  of  pre-admission  is  insufficient , how  will 
it  be  shown  in  the  indicator  diagram  ? 

Answer.  The  effect  of  too  little  pre-admission  is  to  lower  the  pressure 
of  the  steam  at  the  beginning  of  the  stroke,  and  at  high  speeds  there  will 
not  be  time  enough  nor  sufficient  opening  of  the  steam-port  to  supply  the 
deficiency  after  the  stroke  has  commenced.  The  effect  of  this  is'shown 
by  the  dotted  lines,  in  fig.  288,  which  shows  that  maximum  pressure  was 
not  reached  until  some  time  after  the  beginning  of  the  stroke.  With  a 
link  motion,  if  the  steam  is  cut  off  short  the  port  is  opened  but  a small 
distance,  which  is  sufficient  to  maintain  the  pressure  at  the  beginning  of 
the  stroke,  when  the  piston  is  moving  comparatively  slowly.  But  when 
the  piston  has  moved  a short  distance,  its  motion  is  accelerated  and  at  the 
same  time  the  port  is  being  gradually  closed  by  the  valve,  and  the  area 
available  for  the  admission  of  the  steam  is  thus  gradually  diminished. 
Consequently,  the  steam  cannot  enter  fast  enough  to  follow  the  piston, 
and  the  pressure  falls,  so  that  the  admission  line,  A B,  is  no  longer  hori- 
zontal, but  droops,  as  shown  in  figs.  287  and  288. 

Another  cause  of  loss  of  pressure  at  the  commencement  of  the  stroke, 
when  the  steam  is  worked  expansively,  is  the  partial  condensation  of  the 
entering  steam,  which  takes  place  in  consequence  of  its  coming  in  contact 
with  the  sides  of  the  steam-ways  and  walls  of  the  cylinder,  which  have  been 
previously  cooled  down  by  contact  with  the  exhaust  steam  of  the  preceding 
stroke.  This  condensation  of  the  fresh  steam  causes  a very  serious  loss  of 
efficiency  in  the  steam-engine.* 

Question  396.  If  the  ope7iing  of  the  steam-ports  during  admission  is 
too  small,  what  will  be  the  form  of  the  diagram  ? 

Answer.  The  effect  will  be  very  much  the  same  as  that  produced  by 
too  little  pre-admission  or  lead — that  is,  the  pressure  in  the  cylinder  will 
be  much  lower  than  in  the  boiler  and^will  fall  rapidly  during  the  periods 
of  admission,  as  shown  in  fig.  288. 

Question  397.  What  defects  may  be  indicated  by  the  expansion  curve 
of  indicator  diagram  ? 

Answer.  If  the  cylinders  are  not  well  protected,  and  there  is  much  loss 
of  heat  from  radiation,  there  will  be  a rapid  fall  of  pressure  during  the 
period  of  expansion,  which  will  be  shown  by  the  expansion  curve  falling 
below  the  theoretical  curve.  If,  on  the  contrary,  the  indicator  curve  is 


* “The  Steam-Engine,"  by  George  C-  V.  Holmes. 


The  Valve  Gear. 


33' 


much  above  the  theoretical  curve,  it  may  be  caused  by  a leak  in  the  valve. 
As  steam  is  quite  as  likely  to  leak  from  the  steam-port  into  the  exhaust 
as  from  the  steam-chest  into  the  steam-port,  a valve  which  is  not  tight 
may  produce  just  the  contrary  effect  upon  the  indicator  diagram.  As  it 
is  usually  quite  easy  to  detect  a leak  in  the  valve  by  other  means,  the  use 
of  the  indicator  for  this  purpose  is  unnecessary.  Attention  is  called  to  it, 
however,  to  show  the  impossibility  of  getting  results  of  any  value  with 
the  indicator  if  the  valves  are  not  steam-tight. 

Question  398.  What  should  be  observed  regarding  the  exhaust  line  of 
the  indicator  diagram  ? 


Fig.  292.  Indicator  Diagram. 

Answer.  The  most  important  point  to  be  observed  is,  whether  the 
pressure  at  the  end  of  the  stroke  is  reduced  as  low  as  possible,  as  at  high 
speeds  it  is  usually  much  more  difficult  to  exhaust  the  steam  from  than  to 
admit  it  into  the  cylinder.  As  already  stated,  the  blast  in  the  chimney 
makes  it  almost  impossible  to  exhaust  the  steam  to  atmospheric  pressure 
when  the  locomotive  is  running  fast.  If  the  steam  is  released  too  late  in 
the  stroke,  as  already  explained,  there  will  not  be  time  enough  nor  suf- 
ficient opening  of  the  port  to  allow  the  confined  steam  to  escape  from  the 
cylinder  before  the  end  of  the  stroke,  and  this  will  be  indicated  on  the 
diagram  by  the  space  between  the  line  of  back  pressure  and  the  at- 
mospheric line  during  the  commencement  of  the  return  stroke,  as  shown 
in  figs.  290-292. 


338 


Catechism  of  the  Locomotive. 


Question  399.  What  should  be  observed  regarding  the  line  of  back 
pressure  ? 

Answer.  The  most  important  point  is,  that  it  should  approximate  as 
closely  as  possible  to  the  atmospheric  line,  as  all  the  back  pressure  not 
only  diminishes  the  efficiency  of  the  engine,  but  is  a total  loss  of  energy. 
Too  much  inside  lap  will  increase  the  amount  of  back  pressure,  but  gen- 
erally it  is  more  influenced  by  the  area  of  the  blast  orifices  than  by  any 
other  cause.  Every  effort  should  be  made,  therefore,  to  have  them  as 
large  as  possible,  and  yet  have  the  boiler  make  as  much  steam  as  is 
needed. 

When  only  one  blast  orifice  is  used  for  both  cylinders,  it  often  happens 
that  when  the  steam  is  exhausted  from  the  one  cylinder  it  “ blows  ” over 
into  the  other,  and  thus  produces  an  additional  amount  of  back  pressure. 
This  is  shown  by  a rise  or  “hump”  in  the  line  of  the  back  pressure,  as  in- 
dicated by  the  dotted  Yme,f'g'  h'  i'j',  in  fig.  287. 

Question  400.  What  good  effects  result  from  compression  ? 

Answer.  It  serves  to  arrest  the  motion  of  the  piston  at  the  end  of  the 
stroke.  As  was  explained  in  Chapter  IX,  the  motion  of  a piston  in  the 
cylinder  of  a steam-engine  is  not  a uniform  one,  but  increases  in  speed 
from  the  beginning  of  the  stroke  to  the  middle,  and  diminishes  in  speed 
from  the  middle  to  the  opposite  end.  It  is  obvious  that  if  the  momentum, 
or  actual  energy  stored  up  in  the  piston  or  other  reciprocating  parts  after 
they  have  passed  the  middle  of  the  stroke,  added  to  the  pressure  behind 
the  piston,  is  greater  than  the  resistance  offered  by  the  crank,  the  motion 
of  the  latter  will  then  be  accelerated  and  thus  conveyed  to  the  moving 
engine  and  train.  If,  however,  there  is  any  momentum  in  the  piston 
when  it  reaches  the  end  of  the  stroke,  evidently  it  can  exert  no  power  to 
cause  the  crank  to  revolve,  but  the  momentum  must  be  expended  by  pro- 
ducing a pressure  on  the  crank-pin  and  thus  on  the  axle-boxes.  Not  only 
will  such  a pressure  not  cause  the  crank  to  revolve,  but  it  will  be  more 
difficult  to  turn  the  crank  with  such  a pressure  against  it  than  it  would  be 
without.  The  momentum  of  the  piston  and  other  reciprocating  parts  at 
dead  points,  therefore,  creates  a resistance  to  the  movement  of  the  crank 
instead  of  helping  to  turn  it.  It  will  also  be  observed  that  after  the  crank 
has  moved  slightly  from  the  dead-point,  any  pressure  on  the  piston  will 
exert  very  little  force  which  will  tend  to  turn  the  crank.  In  fact,  the 
nearer  the  piston  is  to  the  end  of  the  stroke  the  greater  is  the  proportion 
which  the  friction  of  the  crank-pin  and  axle  bears  to  the  useful  effect  of 
the  strain  in  causing  the  crank  to  turn.  Calculation  shows  that  for  about 


The  Valve  Gear. 


339 


three  degrees  on  either  side  of  the  dead-points,  the  effect  of  pressure  on 
the  crank-pin  is  actually  to  retard  the  engine.  If,  then,  the  piston  reaches 
the  end  of  the  stroke  with  a certain  amount  of  momentum  stored  up  in  it, 
which  is  expended  by  producing  pressure  on  the  crank,  then  it  will  not 
only  be  a waste  of  energy  but  a double  waste  by  retarding  the  motion  of 
the  crank.  If,  however,  this  energy  can  be  absorbed  by  compressing 
steam  which  will  fill  the  clearance  spaces,  it  will  not  only  prevent  the  re- 
tarding effect  referred  to,  but  the  energy  in  the  piston  and  other  parts  will 
be  converted  into  steam  pressure,  which  will  be  given  out  in  useful  work 
during  the  next  stroke.  It  would,  of  course,  be  impossible  to  arrest  the 
motion  of  the  piston  instantly,  and  therefore  its  momentum  is  gradually 
absorbed  from  the  time  compression  begins  until  it  reaches  the  end  of  the 
stroke.  As  the  energy  of  a moving  body  is  equal  to  its  weight  multiplied 
by  the  square  of  its  speed,  it  is  obvious  that  to  overcome  this  a different 
amount  of  compression  would  be  required  for  each  speed,  and  also  that  it 
must  be  adjusted  to  the  weight  of  the  moving  parts.  Such  adaptation  is 
not  practicable  on  locomotives,  nor  does  the  link-motion  enable  us  to 
alter  the  amount  of  compression  with  so  much  exactness ; but  the  explana- 
tion shows  the  value  of  increasing  the  amount  of  compression  with  the 
speed,  which  fortunately  the  peculiarities  of  the  shifting-link  motion 
enables  us  to  do  without  difficulty. 

QUESTION  401.  How  does  a link-motion  increase  the  amount  of  compres- 
sion with  the  speed? 

Answer.  When  a locomotive  is  running  fast  the  steam  is  cut  off  short, 
and  the  lead  and  the  amount  of  compression  increases  as  the  period  of 
admission  diminishes. 

Question  402.  What  cause  produces  the  form  of  diagram  represented 
by  fig.  292  ? 

Answer.  It  is  produced  by  excessive  compression,  which  causes  the 
pressure  in  the  cylinder  to  rise  above  boiler  pressure  before  pre-admis- 
sion begins.  As  soon  as  the  port  is  opened,  part  of  the  steam  in  the  cyl- 
inder flows  back  into  the  steam-chest,  and  thus  the  pressure  is  reduced,  as 
shown  by  the  diagram. 

Question  403.  What  will  an  indicator  diagram  show  ? 

Answer.  It  will  show  : 

1.  The  pressure  of  steam  in  the  cylinder  at  the  beginning  of  the 
stroke  of  the  piston,  or  the  initial  pressure,  as  it  is  called. 

2.  Whether  the  initial  pressure  is  increased  pr  diminished  during  the 
period  of  admission, 


340 


Catechism  of  the  Locomotive. 


3.  The  point  of  cut-off. 

4.  The  pressure  during  the  whole  period  of  expansion. 

5.  The  point  of  release — i.  e.t  when  the  exhaust  is  opened. 

6.  The  rapidity  with  which  the  exhaust  takes  place. 

7.  The  back  pressure  on  the  piston. 

8.  The  point  at  which  the  exhaust  is  closed. 

9.  The  compression  after  the  exhaust  is  closed. 

10.  The  power  which  is  driving  the  engine. 

11.  Leakage  of  the  valve  or  piston. 

QUESTION  404.  What  are  the  principal  causes  which  affect  the  form  of 
an  indicator  diagram  ? 

Answer.  1.  The  friction  of  the  steam  in  the  pipes  and  ports. 

2.  The  variable  size  of  the  openings  of  the  steam-ports  as  caused  by 
the  gradual  motion  of  the  slide-valve. 

3.  The  action  of  the  internal  surfaces  of  the  cylinder  in  causing  the 
condensation  and  partial  re-evaporation  of  some  of  the  entering  steam. 

4.  The  steam  contained  in  the  clearance  spaces  which  affects  the 
curve  of  expansion. 

5.  The  gradual  opening  of  the  exhaust-port,  which  makes  it  necessary 
to  release  the  steam  too  early  in  the  stroke. 

6.  The  friction  of  the  exhaust  passages,  which  increases  the  back  pressure. 

7.  The  clearance  spaces,^  which,  combined  with  the  unavoidable  na- 
ture of  the  action  of  a slide-valve  driven  by  a link-motion  and  the  momen- 
tum of  the  moving  parts,  make  compression  necessary.* 

Question  405.  How  can  we  determine  whether  the  steam  is  distributed 
in  the  cylinders  to  the  best  advantage , and  how  can  we  discover  the  fault , if 
there  is  one , in  the  link-motion  ? 

Answer.  The  indicator  will  show  the  action  of  the  steam  in  the  cylin- 
der, and  motion-curves  drawn  with  the  instrument  described  in  answer  to 
Question  367  will  show  the  exact  movement  of  the  valve.  By  comparing 
the  indicator  diagram  with  the  motion-curves,  the  one  will  show  the  de- 
fects in  the  other.f 

Question  406.  To  what  extent  can  the  movement  of  the  valve  be  modi- 
fied by  alterations  in  the  proportions  of  the  link-motion  ? 

Answer.  The  motion  of  the  valve  is  susceptible  of  an  almost  infinite 

* Questions  403  and  404  were  suggested  by  George  C.  V.  Holme’s  excellent  book  on  the  steam- 
engine,  and  the  answers  thereto  are  in  substance  taken  therefrom. 

tSee  description  of  Richards’  Improved  Steam-Engine  Indicator,  with  directions  for  ifs 
use,  by  Charles  T.  Porter,  London. 


The  Valve  Gear. 


341 


number  of  changes,  by  different  variations  and  combinations  of  propor- 
tions of  the  working  parts  of  the  link-motion.  These  changes  are,  how- 
ever, limited  by  the  general  laws  which  govern  the  motion  of  eccentrics, 
and  therefore  cannot  influence  the  motion  of  the  valve  beyond  certain 
limits.  Hardly  any  variation  can  be  made  either  in  the  proportions  or 
arrangement  of  the  working  parts  which  will  not  have  some  influence 
upon  the  movement  of  the  valve.  Aside  from  the  proportions  of  the 
valve  itself,  which  have  already  been  discussed,  the  throw  of  the  eccentrics, 
the  length  of  the  rods  and  of  the  link,  the  point  of  connection  of  the  rods 
with  the  link,  the  point  of  suspension,  the  position  of  the  lifting-shaft, 
the  length  of  the  arms,  the  length  and  position  of  the  rocker-arms,  will 
each  of  them  effect  the  distribution  of  steam.  The  number  of  combina- 
tions of  all  these  different  proportions  is,  of  course,  almost  infinite,  and 
therefore  any  full  discussion  of  them  will  be  impossible  here. 

QUESTION  407.  What  are  the  most  important  points  which  require 
attention  in  designing  a link-motion  ? 

Answer . It  should  be  proportioned  so  that — 

1.  The  lead  and  the  period  of  admission  should  be  the  same  for  each 
end  of  the  cylinder,  at  each  point  of  cut-off,  and,  if  possible,  in  back  as 
well  as  forward  gear. 

2.  The  width  of  opening  for  both  admission  and  exhaust  should  be  as 
large  as  possible  when  steam  is  cut  off  short. 

3.  The  exhaust  or  pre-release  should  occur  early  enough  and  be  main- 
tained long  enough  to  reduce  back-pressure  as  low  as  possible. 

Question  408.  In  designing  valve-gear  how  is  it  usually  tested? 

Answer.  Usually  a full-sized  model  is  made,  the  various  parts  of  which 
are  made  adjustable,  so  that  the  proportions  and  position  of  the  different 
parts  may  be  varied,  in  order  that  the  best  possible  movement  of  the  valve 
may  be  obtained.  If  mechanism  for  drawing  diagrams  of  the  motion  of 
the  valve,  similar  to  that  illustrated  in  fig.  270,  is  added  to  the  model,  the 
action  of  the  valve-gear  can  be  completely  delineated. 

Question  409.  How  can  the  lead  and  periods  of  admission  of  a slide- 
valve  be  equalized  at  each  end  of  the  stroke  of  the  piston  ? 

Answer.  It  is  impossible  to  make  the  periods  of  admission  absolutely 
alike  for  every  point  of  cut-off  in  both  fore  and  back  gear.  It  is,  there- 
fore, customary  to  disregard  the  back  gear,  as  engines  are  worked  but 
little  with  the  link  in  that  position.  Even  for  forward  gear  the  periods 
of  admission  cannot  be  made  exactly  alike  for  each  end  of  the  cylinder 
and  for  each  point  of  cut-off,  and  therefore  it  is  usual  to  majce  the  periods 


342 


Catechism  of  the  Locomotive. 


of  admission  alike  for  half-gear  forward,  in  which  position  the  link  is 
worked  most. 

The  periods  of  admissions  for  the  front  and  back  ends  of  the  cylinder 
can  be  changed  most  in  relation  to  each  other  by  altering  the  position  of 
the  point  of  suspension  on  the  link.  This  can  be  done  either  by  moving 
this  point  up  or  down,  or  horizontally.  Usually  links  are  suspended  from 
a point  halfway  between  the  points  of  connection  of  the  eccentric-rods 
and  from  ^ to  f inch  back  of  the  centre  line  of  the  slot  in  the  link.  A 
somewhat  better  distribution  can  be  secured  by  suspending  them  about 
3 inches  above  the  centre,  but  the  suspending-links  must  then  be  made  so 
short  that  they  are  subjected  to  very  great  strains  by  the  motion  of  the 
link,  and  this  evil  is  usually  considered  much  greater  than  the  advantage 
which  is  gained  thereby  in  the  more  equal  distribution.  The  point  at 
which  the  upper  end  of  the  suspension-link  is  hung  also  influences  the 
relative  amount  of  admission  front  and  back.  This  point,  of  course,  varies 
as  the  end  of  the  lifting-arm  is  raised  or  lowered.  The  best  position  for  the 
lifting-shaft  and  the  length  of  its  arm  can  be  determined,  perhaps,  most 
satisfactorily  by  placing  the  link  in  full-gear  forward,  then  moving  the 
point  of  suspension  of  the  upper  end  of  the  link-hanger  horizontally,  so 
that  the  front  and  back  admission  will  be  alike,  and  then  marking  this 
position.  The  same  process  should  then  be  repeated  for  half-gear  and 
for  the  shortest  point  of  cut-off.  If  the  position  of  the  lifting-shaft  and  the 
length  of  its  arm  are  then  so  arranged  that  the  end  of  the  latter  will  move 
through  the  three  points  which  have  been  thus  determined,  the  admission 
will  be  very  nearly  equal  for  each  end  of  the  cylinder.  Usually,  however, 
it  is  impossible  to  arrange  the  shaft  and  arm  so  that  they  will  conform 
exactly  to  these  conditions,  and  therefore  an  approximation  is  made  which 
will  come  as  near  as  possible  to  what  is  required.  It  may  be  stated,  how- 
ever, that  the  lifting-shaft  should  be  kept  as  low  as  possible,  so  as  not  to 
interfere  with  the  eccentric-rods.  In  some  cases  the  shaft  has  been  sus- 
pended from  the  boiler,  so  that  the  outside  eccentric-rod  would  work  past 
or  over  the  end  of  the  lifting-shaft,  thus  allowing  the  latter  to  be  located 
lower  than  would  otherwise  be  possible. 

QUESTION  410.  Which  parts  of  the  link-motion  have  the  greatest  influ- 
ence on  the  distribution  of  steam  ? 

Answer.  The  lap  of  the  valve  and  the  throw  of  the  eccentrics.  The 
effect  of  any  change  of  these  upon  the  distribution  is  very  similar  to  that 
produced  if  a single  eccentric  is  used,  which  was  explained  in  the  answers 
to  Questions  146  and  147. 


The  Valve  Gear. 


343 


Question  411.  What  is  the  effect  upon  the  admission  of  increasing 
the  throw  of  the  eceentrics  with  the  same  lap  ? 

Answer.  As  already  explained,  the  effect  is  to  increase  the  period  of 
admission,  or,  in  other  words,  to  cut  off  later  in  the  stroke,  and  also  to 
increase  the  width  of  the  opening  of  the  steam-port  or  the  distance  which 
> the  valve  throws  over  the  port.  This  has  an  important  influence  upon 
the  admission  when  the  link-motion  is  used. 

Question  412.  What  is  meant  by  the  angular  advance  of  the  eccen- 
trics ? 

Answer.  It  is  the  angle  which  a line,  e /,  fig.  293,  drawn  through  the 


centre,/,  of  the  axle  and  the  centre,^,  of  the  eccentric  makes  with  a ver- 
tical line,  a b , also  drawn  through  the  centre  of  the  axle  when  the  crank 
is  on  one  of  the  dead-points  or  centres.  Thus,  in  fig.  293,  the  crank-pin, 
Af  is  represented  on  the  front  centre.  In  order  to  give  the  valve  the 
necessary  lead,  the  eccentric  must  be  moved  back  of  the  vertical  line,  a b. 
The  angle,  bfe,  which  the  line,  e f (drawn  through  the  centre,  g,  of  the 
eccentric  and  /of  the  axle)  makes  with  the  vertical  line  is  called  the  angu- 
lar advance. 

Question  413.  What  is  meant  by  linear  advance? 

Answer.  By  linear  advance  is  meant  the  distance  which  the  valve  has 
moved  from  its  middle  position  at  the  beginning  of  the  stroke  of  the 
oiston.  This,  when  the  two  rocker-arms  are  the  same  length,  is  the  same 


344 


Catechism  of  the  Locomotive. 


as  the  distance,^  h,  of  the  centre  of  the  eccentric,^,  from  the  vertical 
line,  a b,  fig.  293. 

Question  414.  Why  does  the  cut-off  occur  earlier  with  an  eccentric 
having  a short  throw  than  with  one  which  gives  more  travel  to  the  valve  ? 

Answer.  Because  it  is  necessary  to  give  the  eccentric  with  the  short 
throw  more  angular  advance — that  is,  it  must  be  set  “ farther  ahead  ” in 
order  to  give  the  valve  the  required  lead.  This  is  illustrated  in  fig.  294, 


in  which  a section  of  a valve,  F,and  ports,  eg  and  e , are  represented.  In 
order  to  simplify  the  diagram  as  much  as  possible,  the  rocker  is  left  out 
and  the  valve  is  supposed  to  be  moved  by  the  rod,  R,  directly  from  the 
centre,  a,  of  the  eccentric.*  The  effect  of  the  angularity  of  the  connect- 
ing-rod and  eccentric-rod  is  also  neglected.  The  circle,  a b e f,  represents 
the  path  of  the  centre  of  an  eccentric  having  5 inches  throw,  and,  h s i j, 
the  path  of  one  having  3^  inches  throw.  In  order  to  give  the  valve  the 
required  lead,  which  is  supposed  to  be  just  line-and-line  at  the  beginning 
of  the  stroke,  the  linear  advance  of  the  valve  must  be  equal  to  the  lap,  or 
l inch.  If,  therefore,  we  draw  a line,  p q,  parallel  to  the  vertical  centre 
line,  e k,  and  £ inch  from  it,  the  intersection  of  p q at  a and  h with  the 
paths  of  the  eccentric  will  be  the  centres  of  the  eccentrics.  If  through 
these  centres  and  the  centre  of  the  circle,  lines  o q and  oh  be  drawn,  the 
angles,  k o q and  l o m,  which  they  make  with  the  vertical,  e k,  will  repre- 
sent the  angular  advance.  It  will  be  seen  from  these  lines,  and  by  com- 


* It  will  be  seen  that  this  causes  the  position  of  the  centre  of  the  eccentric  to  be  reversed. 


/ 


The  Valve  Gear.  845 

paring  these  two  angles,  that  in  order  to  give  the  valve  the  required  lead, 
it  is  necessary  to  give  the  eccentric  with  the  small  travel  more  angular 
advance  than  is  necessary  for  the  one  with  the  larger  throw.  It  is  obvious, 
too,  that  when  the  centre  of  the  larger  eccentric  has  reached  the  point,  b, 
the  valve  will  have  received  its  greatest  travel,  and  that  when  it  reaches 
p,  the  steam-port,  c,  will  again  be  closed  or  the  steam  cut  off.  If  the 
small  eccentric  is  employed,  the  valve  will  have  its  maximum  travel  when 
the  centre,  h,  reaches  s,  and  the  port  will  be  closed  when  it  reaches  /.  By 
drawing  lines,  op  and  o n,  through  / and/,  it  will  be  seen  that  from  the 
beginning  of  the  stroke  until  the  steam  is  cut  off,  if  the  large  eccentric 
is  employed,  it,  and  consequently  the  shaft  and  crank,  must  move  over  an 
angle  measured  by  the  arc,  q t p.  If  the  small  eccentric  is  used,  it  and  the 
crank  must  move  through  an  angle  measured  by  the  arc,  it  t n.  In  other 
words,  the  crank  must  turn  a considerable  greater  distance  before  steam 
is  cut  off  with  an  ^centric  having  a large,  than  with  one  having  a small, 
throw. 

It  is  also  quite  obvious  from  fig.  294  why  the  port  is  opened  a shorter 
distance  with  a small  than  with  a large  eccentric.  The  distances,  o s and 
o b,  are  equal  to  half  the  throws  of  the  eccentrics,  or  If  or  2f  inches.  The 
linear  advance,  o r,  is  in  both  cases  £ inch,  and  therefore  after  the  port 
begins  to  open,  the  valve  will  be  moved  by  the  small  eccentric,  a distance 
which  is  equal  to  If — inches,  and  by  the  large  one  2f— f=lf  inches. 

Question  415.  What  is  the  effect  on  the  admission  of  giving  an  eccen- 
tric with  a small  throw  the  same  angular  advance  as  one  with  a large  throw , 
and  then  reducing  the  lap  of  the  valve  so  that  the  lead  will  be  the  same  in 
both  cases? 

Answer.  The  admission  and  the  cut-off  will  then  occur  at  the  same 
points  of  the  stroke,  but  the  ports  will  not  be  opened  so  wide.  This  is 
illustrated  in  fig.  295,  in  which  the  paths  of  two  eccentrics  having  the  same 
throw  as  those  in  fig.  246  are  represented.  The  centre,  a,  of  the  larger 
eccentric  is  represented  in  the  same  position  in  fig.  295  as  in  fig.  294.  If 
a line  is  drawn  from  the  centre  of  the  larger  eccentric  to  o,  the  centre  of 
the  axle,  and  if  the  centre,  h,  of  the  smaller  eccentric  is  located  on  the 
intersection  of  this  line  with  the  circle,  h s ij , which  represents  its  path, 
then  the  smaller  eccentric  will  have  the  same  angular  advance,  but  the 
linear  advance  measured  by  the  distance,  o t,  will  be  only  -f  inch.  If  the 
valve  has  the  same  lap  as  in  fig.  294  its  steam  edges  at  the  beginning  of 
the  stroke — if  the  small  eccentric  is  employed — will  occupy  the  position 
represented  by  the  dotted  lines,  A and  B.  If  these  edges  are  cut  off  and 


346 


Catechism  of  the  Locomotive. 


the  valve  is  made  as  shown  by  the  full  lines  and  shading,  then  it  will  have 
the  same  lead  as  in  fig.  294.  It  is  obvious,  too,  that  if  the  smaller  eccen- 
tric has  the  same  angular  advance,  its  centre  will  move  from  h to  i,  at 
which  point,  with  the  reduced  lap,  the  steam  will  be  cut  off  at  the  same 
time  that  the  centre  of  the  large  eccentric  will  move  from  a to  p,  at  which 
point  it  cuts  off  the  steam  with  the  valve  having  the  large  lap.  There  is, 
however,  this  difference  in  the  distribution,  that  in  the  one  case  the  valve 
opens  the  port  a distance  equal  to  t s,  and  in  the  other  a distance  equal  to 
r b.  As  o t is  equal  to  the  linear  advance  of  the  small  eccentric,  or  £ inch, 
and  o s to  half  the  throw  of  the  eccentric,  or  If,  t s is  equal  to  If  — f=l£ 
inches.  The  distance  r b,  as  shown  above,  is  equal  to  2£ — £=1£  inches, 
so  that  the  effect  produced  upon  the  admission  of  using  an  eccentric  with 
a small  throw  and  corresponding  amount  of  lap  is,  that  the  ports  are  not 
opened  so  wide  as  with  an  eccentric  having  a larger  throw. 

Question  416.  Howdoeccentricswith  a short  throw andvalves  with  a cor- 
responding amount  of  lap,  affect  the  admissionwith  a link-motion  as  compared 
with  eccentrics  having  a larger  amount  of  throw  and  greater  lap  of  valve? 

Answer.  The  chief  difference,  as  has  been  explained,  is  that,  with 
eccentrics  having  a short  throw  and  valves  with  a corresponding  amount 
of  lap,  the  ports  are  not  opened  so  wide  for  the  same  period  of  admis- 
sion as  they  are  with  eccentrics  having  more  throw  and  valves  with 
greater  lap.  Thus  a series  of  motion-curves  is  shown  in  fig.  296,  drawn 
with  a model  of  a link-motion  like  that  illustrated  in  fig.  270.  The 
eccentrics  had  5 inches  throw,  and  the  valve  £ inch  lap  outside  and 
inch  inside.  Fig.  297  represents  a series  of  curves,  drawn  with  the  same 
arrangement  of  valve-gear,  excepting  that  the  eccentrics  had  3£  inches 
throw  and  the  valve  £ inch  lap.  In  both  cases  the  curves  represent  the 
motion  of  the  valve  when  cutting  off  at  the  same  point  of  the  stroke. 
The  following  table  will  show  the  relative  amount  of  opening  of  the  port : 


Point  of  Cut-Off. 

Width  of  Opening  of  Steam-Port. 

Eccentric  5 inches  throw. 

Eccentric  inches  throw. 

6 inches. 

375  inch. 

3S2  inch. 

10  “ 

U “ 

7 

32 

15  “ 

% “ 

% “ 

18  “ 

32 

tt  “ 

21  “ 

iy4*  “ 

“ 

* The  valve  throws  over  the  steam-port  % inch  at  this  point. 


«£1 

20 

19 

18' 

17' 

16' 

15' 

14' 

13' 

12’ 

i i 

lo! 

9' 

8' 

7' 

6' 

5' 

4' 

3' 

2' 

l' 

0' 


0 


The  Valve  Gear. 


349 


It  will  be  seen  from  this  that  the  eccentric  with  5 inches  throw  gives  a 
greater  width  of  opening  for  every  point  of  cut-off  than  the  one  with  3^ 
inches  throw.  For  the  higher  admissions  this  is  not  important,  but  when 
steam  is  cut  off  short  it  will  be  observed  that  the  width  of  the  opening 
is  very  small.  At  high  speeds  the  small  opening  is  a great  disadvan- 
tage. 

Question  417.  Has  it  been  determined  what  amount  of  opening  is 
required for  given  speeds  of  the  piston  ? 

Answer.  Not  with  any  degree  of  accuracy.  It  is  customary  to  make 
the  area  of  the  ports  about  one-tenth  of  the  piston.  It  is  certain,  how- 
ever, that  with  steam-ports  of  this  proportion,  excepting  at  high  speeds, 
an  opening  considerably  less  than  their  whole  area  is  sufficient  to  main- 
tain steam  nearly  equal  to  boiler  pressure  in  the  cylinders.  One  of  the 
defects  of  the  link-motion  is  that  the  opening  of  the  port  is  very  small 
when  the  steam  is  cut  off  short.  When  the  valve  begins  to  close  the 
port  the  speed  of  the  piston  is  increasing  so  that  it  is  impossible  to  main- 
tain full  boiler  pressure  during  the  whole  period  of  admission.  It  is  best, 
therefore,  to  secure  the  largest  practicable  opening  of  the  ports  for  the 
lower  points  of  cut-off. 

Question  418.  What  are  the  proportions  of  the  valves  and  eccentrics 
used  in  the  ordinary  practice  in  this  country  ? 

Answer.  Excepting  for  very  light  locomotives  the  maximum  travel 
varies  from  to  inches,  the  outside  lap  from  f to  IF  inches,  the  inside 
lap  from  fa  to  fa  inch,  and  the  lead  in  full  gear  from  fa  to  F inch. 

Question  419.  What  should  be  the  width  of  the  bridge  between  the 
steam  and  exhaust-ports  ? 

Answer.  It  is  usually  made  about  the  same  thickness  as  the  sides  of 
the  cylinder,  in  order  to  secure  a good  casting ; but  sometimes  it  is  neces- 
sary to  make  it  wider,  in  order  to  prevent  steam  from  escaping  from  the 
steam-chest  into  the  exhaust,  which  is  apt  to  be  the  case  if  a valve  has 
little  lap  and  a long  travel. 

Question  420.  What  determines  the  width  of  the  exhaust-ports  ? 

Answer.  The  throw  of  the  valve.  This  will  be  clear  if  we  refer  to  fig. 
70.  As  explained  in  answer  to  Question  134,  the  port,  g,  should  be  wide 
enough  so  that  when  the  valve  is  at  the  end  of  its  travel  the  opening,  h i, 
of  the  exhaust-port  is  not  contracted  too  much.  If  this  opening  is  not 
wide  enough  it  will  prevent  the  free  escape  of  the  exhaust  steam  and 
increase  the  back  pressure. 

It  is,  therefore,  best  to  make  the  exhaust-port  so  wide  that  with  the 


350 


Catechism  of  the  Locomotive. 


greatest  travel  of  the  valve  the  width  of  its  opening  will  be  nearly  equal 
to  the  width  of  the  steam-ports. 

Question  421.  What  effect  does  the  steam  have  on  a slide-valve  ? 

Answer.  It  exerts  a pressure  nearly  or  quite  equal  to  the  area  of  the 
top  of  the  valve  multiplied  by  the  pressure  of  the  steam  on  that  area. 
Thus,  a valve  whose  outside  dimensions  are  9 x 18  inches  would  have  an 
area  of  162  square  inches.  If  a boiler  pressure  of  140  lbs.  per  square  inch 
is  exerted  on  the  whole  of  this  area  it  would  be  equal  to  162  x 140  = 
22,680  lbs.  The  actual  pressure  exerted  by  the  steam  on  the  valve  is, 
however,  very  irregular,  as  during  some  portions  of  the  stroke  the  steam 
in  the  ports  under  the  valve  exerts  an  upward  pressure,  which  opposes 
that  on  top.  The  pressure  on  top  is  also  influenced  by  the  fit  of  the 
valve  to  its  seat.  If  it  is  not  steam-tight  more  or  less  steam  will  get 
between  the  valve  and  its  seat,  and  thus  counteract  the  pressure  on  top, 
whereas  if  the  valve  is  perfectly  steam-tight,  no  such  action  will  occur. 
In  any  event,  the  pressure  on  top  of  slide-valves  is  very  considerable. 

Question  422.  How  much  of  the  whole  power  of  the  engine  is  absorbed 
in  moving  slide-valves  ? 

Answer.  Experiments  * with  small  engines  have  shown  that  from  one 
to  two  per  cent,  of  the  whole  power  is  absorbed  in  moving  the  slide- 
valves  when  the  pressure  on  them  is  not  relieved  in  any  way. 

Question  423.  How  is  the  pressure  on  slide-valves  relieved? 

Answer.  By  excluding  the  steam  from  the  top  of  the  valve  so  that  the 
pressure  cannot  be  exerted  on  the  valve.  This  is  done  by  means  of  pack- 
ing on  the  top  of  the  valve,  which  bears  against  a plate  above.  This 
packing  consists  either  of  rings  or  straight  strips  of  metal,  p p,  as  shown 
in  fig.  298.  In  the  Richardson  Balanced  Valve,  which  is  the  one  shown 
by  fig.  298,  the  packing  is  arranged  in  rectangular  form  and  held  in  grooves 
on  top  of  the  valve.  This,  packing  bears  against  a plate,  P,  attached  to 
the  steam-chest  cover,  which  is  planed  and  scraped  so  that  the  surfaces 
of  contact  of  the  packing  against  the  plate  are  steam-tight.  The  packing 
is  also  made  steam-tight  where  it  is  in  contact  with  the  valve,  and  is  held 
up  against  the  plate  by  springs  underneath.  Steam  is  thus  excluded  from 
the  top  of  the  valve,  at  a a.  A hole,  o,  in  the  valve  allows  any  steam 
which  might  leak  past  the  packing  to  escape  into  the  exhaust  cavity,  V. 
A relief  valve,  R,  is  attached  to  the  steam-chest  to  admit  air  into  the 
steam-chest  and  prevent  it  from  being  sucked  in  through  the  exhaust- 

' * See  paper  on  “ The  Power  Required  to  Move  Slide-Valves,”  by  Mr.  C.  M.  Giddings,  read 
at  the  Chicago  Meeting  of  the  American  Society  of  Mechanical  Engineers,  in  1887. 


Fig.  298.  Richardson  Balanced  Valve.  Scale  in.=l  in. 


352 


Catechism  of  the  Locomotive. 


pipes,  when  steam  is  shut  off,  and  the  action  of  the  piston  creates  a par- 
tial vacuum  in  the  steam-chest.  If  air  was  sucked  in  through  the  exhaust- 
pipes.  cinders  and  other  gritty  substances  would  be  drawn  in  with  it,  and 
would  be  liable  to  cut  the  valve-face  and  the  inside  of  the  cylinder. 
When  a vacuum  is  produced  in  the  steam-chest,  the  relief-valve,  R,  is 
raised  up  by  the  pressure  of  the  air  below,  and  it  flows  in  through  open- 
ings underneath,  as  indicated  by  the  arrows. 

Question  424.  How  are  the  notches  in  the  sector  of  the  reversing  lever 
arranged? 

Answer.  They  are  often  arranged  so  that  the  steam  will  be  cut  off  at 
some  full  number  of  inches  of  the  stroke  when  the  reverse  lever  is  in  each 
one  of  the  notches.  They  are  then  located  so  that  the  steam  will  be  cut 
off  at  6,  9,  12,  15,  18  and  21  inches,  or  at  6,  8,  10,  12,  15,  18  and  21  inches 
of  the  stroke.  A notch  is  also  placed  so  as  to  hold  the  link  in  mid-gear. 
In  other  cases  as  many  notches  as  there  is  room  for  are  put  into  the  sec- 
tors. The  latter  seems  to  be  much  the  best  plan,  as  it  gives  more  grada- 
tions in  which  the  valve-gear  can  be  worked,  and  it  is  a matter  of  no  con- 
sequence whatever  in  the  working  of  an  engine  whether  the  steam  is  cut 
off  at  some  full  or  some  fractional  number  of  inches  of  the  stroke. 

Question  425.  Where  is  the  reversing-lever  located  and-  how  is  it  con- 
structed? 

Answer.  It  is  located  in  the  cab  and  above  the  foot-board *,  95,  as  shown 
in  Plate  IV.  It  consists  of  a lever,  20  21,  with  the  fulcrum,  22,  at  its  lower 
end.  The  r ever  sing-rod,  19  21,  which  connects  the  lever  with  the  vertical 
arm,  18,  of  the. lifting-shaft,  is  attached  above  the  fulcrum  of  the  reversing- 
lever.  Fig.  299  represents  a side  view  of  the  lever  on  an  enlarged  scale 
and  with  some  of  the  details  attached,  which  are  omitted  on  Plates  III 
and  IV.  S S'  is  a curved  bar,  which,  in  this  country,  is  usually  called  a 
quadrant,  but  in  England  it  is  called  (and  more  properly)  a sector.  Some- 
times a pair  of  these  are  used  and  they  are  then  placed  one  on  each  side 
of  the  reversing-lever  and  are  fastened  to  some  portion  of  the  engine. 
The  sector  has  notches,  n n n,  cut  in  it  to  receive  the  latch,  l,  which  slides 
in  a clamp,  c,  and  holds  the  reversing-lever  in  the  notch  in  which  it  is 
placed.  This  latch  is  operated  by  a trigger,  t,  which  is  grasped  by  a 
locomotive  engineer  when  he  takes  hold  of  the  handle,  H,  of  the  revers- 
ing-lever. The  trigger  works  on  a pin,  e,  as  a fulcrum,  and  is  attached  to 
the  latch  by  a rod,  r r.  When  the  trigger  is  pressed  up  against  the 

*The  foot-board,  93,  Plates  III  and  IV,  is  a platform  for  the  locomotive  runner  and  fireman 
to  stand  on,  and  is  located  at  the  back  end  of  the  engine. 


Fig.  299.  Reversing-Lever.  Scale  1 in.=l  ft. 


354 


Catechism  of  the  Locomotive. 


handle,  the  latch  is  raised  out  of  the  notches  by  the  rod,  r r,  and  is  pressed 
into  them  again  by  the  spring,  s,  when  the  trigger  is  released.  The 
reversing-rod,  G G',  is  connected  to  the  lever  at  G',  and  is  part  of  the  rod 
indicated  by  the  same  letter  in  fig.  246,  and  is  shown  by  the  dotted 
lines,  19  19,  Plates  III  and  IV. 

Question  426.  How  long  should  the  reversing-lever  be? 

Answer.  The  lever  should  be  sufficiently  long,  so  that  in  throwing  the 
link  from  full-gear  forward  to  full-gear  backward  the  handle,  H,  will  move 
not  less  than  four  times  the  distance  that  the  link  is  moved.  It  is  much 
better  to  give  the  end  of  the  handle  five  or  even  six  times  the  motion  of 
the  link,  as  there  will  then  be  a much  easier  action  in  reversing  the  engine. 
This  will  also  make  it  possible  to  use  longer  sectors  and  give  room  for 
more  notches. 

Question  427.  What  provision  is  made  in  the  reversing-gear  for  over- 
coming or  neutralizing  the  weight  of  the  link  and  other  parts  of  the  valve-gear? 

Answer.  Their  weight  is  counterbalanced  by  the  pressure  of  a spring 
of  some  kind.  In  fig.  246  the  case,  H,  contains  a spiral  spring  (of  the 
form  of  a watch  spring) ; the  inner  end  is  fastened  to  the  shaft,  A,  and 
the  outer  end  to  a portion  of  the  case  which  can  be  turned  around  the 
shaft.  By  this  means  the  tension  of  the  spring  can  be  adjusted,  and 
the  case  is  then  held  in  the  required  position  by  a bolt  shown  below  the 
shaft,  A.  Different  kinds  of  springs  are  used  for  this  purpose,  and 
sometimes  are  attached  to  the  reversing-lever  instead  of  to  the  lifting-shaft. 

Question  428.  What  is  meant  by  “ setting  " a slide-valve  ? 

Answer.  It  means  the  adjustment  of  the  position  of  the  eccentrics  on 
the  axle,  and  the  length  of  the  eccentric-rods  and  valve-stem,  so  that  the 
valves  will  give  the  required  distribution  of  steam. 

Question  429.  How  are  the  valves  of  a locomotive  set? 

Answer.  After  the  wheels,  axles,  main  connecting-rods  and  valve-gear 
are  connected  together,  put  the  rocker-arm  in  its  middle  position,  and 
lengthen  or  shorten  the  valve-stem,  so  that  the  valve  will  then  be  in  the 
centre  of  the  valve-face.  Then  place  the  crank  on  the  forward  centre  and 
the  full  part  of  the  forward  motion  eccentric  above  and  that  of  the  back- 
ward motion  eccentric  below  the  axle,  and  ‘fasten  them  to  the  axle  tem- 
porarily by  tightening  up  the  set-screws.  Then  throw  the  link  down 
until  the  block  comes  nearly  opposite  to  the  end  of  the  eccentric-rod,  and 
turn  the  wheels,*  and  at  the  same  time  observe  whether  the  travel  of  the 

* This  can  be  done  by  moving  the  engine  on  the  track  or  by  raising  it  off  its  wheels,  so  that  the 
latter  can  be  turned  without  moving  the  former.  In  some  shops  a pair  of  rollers  is  put  in  the 
track,  so  that  by  placing  the  driving-wheels  on  them  they  can  be  turned  without  any  difficulty, 


The  Valve  Gear. 


355 


valve  is  equal  to  the  throw  of  the  eccentric,  and  also  whether  It  travels 
equally  on  each  side  of  the  centre  of  the  valve-face.  If  its  travel  is  greater 
than  the  throw  of  the  eccentric,  raise  the  link  up;  if  less,  lower  h down 
until  the  two  are  just  equal,  and  then  mark  the  position  for  the  notches 
on  the  sectors  or  quadrants  to  receive  the  latch  of  the  reversing-lever.  If 
the  valve  does  not  travel  equally  on  each  side  of  the  centre  of  the  valve- 
face,  either  lengthen  or  shorten  the  eccentric-rod,  as  may  be  necessary. 
Repeat  this  operation  for  the  backward  motion,  by  raising  the  link  up 
until  the  block  is  opposite  the  end  of  the  lower  eccentric-rod.  After  hav- 
ing done  this,  go  over  the  whole  process  again  to  see  whether  it  is  all  cor- 
rect. Now  with  the  crank  on  the  forward  centre  and  the  link  in  full-gear 
forward,  loosen  the  set-screws  in  the  forward  eccentric,  and  move  it  around 
the  axle  so  that  the  valve  will  have  the  required  lead,  and  then  fasten  it 
again.  Now  raise  the  link  up  into  full  back-gear,  and  set  the  backward 
eccentric  in  the  same  way.  Then  turn  the  wheels  so  as  to  bring  the  crank 
on  the  back  centre,  and  observe  whether  the  lead  is  correct  for  the  back 
end  of  the  cylinder.  If  it  is  not,  lengthen  or  shorten  the  eccentric-rod  so 
as  to  make  the  lead  alike  at  both  ends,  and  if  then  it  is  too  much  or  too 
little,  it  can  be  increased  or  diminished  by  moving  the  eccentrics  on  the 
axle. 

Great  care  must  be  taken  in  setting  valves  to  be  sure  that  the  cranks 
are  exactly  on  the  centres  or  dead-points,  and  it  is  impossible  to  set  them 
in  that  position  with  sufficient  accuracy  from  the  motion  of  the  piston  or 
cross-head  alone,  and  therefore  the  centres  of  the  crank-pins  should 
always  be  set  so  as  to  conform  to  a line  drawn  through  the  centre  of  the 
cross-head  pin,  crank-pin,  and  the  axle. 

When  the  valves  are  set  it  should  also  be  noticed  whether  the  axle- 
boxes  (whose  construction  will  be  explained  hereafter)  are  in  the  middle 
of  the  jaws  in  the  frames,  and  if  not  they  should  be  moved  to  that  position 
by  driving  wooden  wedges  between  them  and  the  frames,  either  above  or 
below,  as  may  be  required.  The  position  of  the  boxes  has  a very  material 
influence  on  the  valve-gear. 

If  it  is  intended  to  lay  off  the  notches  on  the  sectors  so  as  to  cut  off 
steam  at  certain  definite  points  of  the  stroke,  these  points  should  be  laid 
off  in  the  guides  from  the  motion  of  the  cross-head.  The  latter  being 
placed  in  any  of  the  required  positions  at  which  steam  is  to  be  cut  off,  the 
reversing-lever  should  then  be  moved  so  that  the  link  will  just  close  the 
admission  port.  The  lever  can  then  be  clamped  to  the  sectors,  and  the 
.wheels  turned  so  as  to  show  whether  its  position  is  correct  for  each  end 


356 


Catechism  of  the  Locomotive. 


C*f..the  stroke,.  •Tt:h<Ts:be,en  mentioned  before  that  it  is  impossible  to  get 
the  or/i inary J.mk-motion  to  cut  off  at  exactly  the  same  points  at  both  ends 
pf.  the,  Cyiin-dfcr,  but  a very  close  approximation  can  be  made  by  propor- 
tioning the  different  parts  properly.  As  has  already  been  stated,  it  is  a 
much  better  plan  to  put  as  many  notches  in  the  sectors  as  possible  than 
to  locate  them  for  certain  definite  points  of  the  stroke. 

In  setting  the  valves  of  locomotives,  care  must  be  taken  to  turn  the  wheels 
forward  for  the  forward  motion  and  backward  for  the  backward  motion. 

After  the  valves  are  set,  the  position  of  the  eccentrics  on  the  shaft  should 
be  marked,  so  that  in  case  they  become  loose  on  the  road  they  can  easily 
be  set  again.  It  is  usual,  too,  to  mark  the  position  of  the  valves  with 
centre-punch  marks  on  the  valve-stem  and  on  the  stuffing-box  of  the 
steam-chest,  so  that  with  a gauge  made  for  the  purpose  the  position  of 
the  valve  can  be  determined  without  taking  off  the  steam-chest  cover. 

In  some  cases  the  eccentrics  are  keyed  on,  which  is  done  after  their 
position  is  determined  by  setting  the  valves.  The  ends  of  the  set-screws, 
which  are  used  to  fasten  the  eccentrics,  should  be  cup-shaped  and  case- 
hardened,  so  as  to  hold  as  securely  as  possible  to  the  axle  when  they  are 
screwed  down. 

After  the  valve  is  set  on  one  side  of  the  engine,  that  on  the  other  side 
should  be  tested  for  each  point  of  cut-off,  so  as  to  be  certain  that  the  two 
valves  work  alike.  It  sometimes  happens  that  the  link-hanger  or  sus- 
pension link  on  one  side  must  be  either  lengthened  or  shortened,  so  that 
the  two  links  will  occupy  the  same  relation  to  their  rocker-pins. 

After  the  valves  have  been  set  with  the  pistons  at  the  end  of  the  stroke, 
the  valves  on  each  side  should  be  tested  with  the  pistons  at  half  stroke, 
to  see  whether  they  work  alike  on  each  side  with  the  reversing-lever  in 
different  positions.  It  should  be  noticed  whether  the  link-blocks  stand 
in  the  same  position  in  the  links  at  the  beginning  of  the  stroke  of  each 
piston.  This  can  be  known  by  cutting  a stick  to  fit  between  the  top  or 
bottom  of  the  block  and  the  end  of  the  link.  Sometimes  the  two  hori- 
zontal arms  on  the  reversing-shaft  are  not  in  the  same  horizontal  line, 
and  the  shaft  must,  therefore,  be  heated  and  twisted  so  as  to  make  the 
valve-motion  work  alike  on  both  sides. 

If  the  valves  are  set  when  the  engine  is  cold,  they  should  be  tested  after 
it  has  been  fired  up,  as  the  expansion  of  the  parts  may  affect  the  action 
of  the  valves. 


CHAPTER  XVII. 


ACTION  OF  THE  PISTONS,  CRANKS,  AND  DRIVING-WHEELS. 

QUESTION  430.  Is  the  whole  of  the  net  effective  pressure  which  is  ex- 
erted on  the  pistons  com7nunicated  to  the  crank-pin  ? 

Answer.  No  ; a part  of  this  pressure  is  exerted  to  overcome  the  inertia 
of  the  pistons  and  other  reciprocating  parts  during  the  first  half  of  the 
stroke,  while  the  back  pressure  resists  their  movement  and  helps  to  stop 
them  at  the  end  of  the  stroke. 

QUESTION  431.  How  can  we  show  the  pressure  which  is  exerted  on  the 
crank-pin  ? 

Answer.  By  first  constructing  a diagram  similar  to  fig.  97,  to  show  the 
pressure  for  any  given  speed  which  must  be  exerted  on  the  piston  during 
the  first  half  of  the  stroke  to  accelerate  it,  and  that  which  must  resist  it  to 
bring  it  to  a state  of  rest  during  the  last  half,  and  then  laying  off  the  net 
effective  pressure,  as  indicated  in  fig.  291,  on  the  line  that  represents  the 
pressure  which  must  be  imparted  to  and  is  given  out  by  the  piston. 

Thus,  a line,  E F,  fig.  300,  should  be  drawn  to  represent  the  length  of 
the  stroke  on  the  same  scale  as  that  used  for  H D,  fig.  291.  E F may  also 
represent  the  line  of  atmospheric  pressure.  From  the  extremity,  E,  a per- 
pendicular, E N,  should  then  be  drawn,  below  E F,  and  another,  F L, 
from  F,  above  E E.  The  centrifugal  force  of  the  reciprocating  parts 
should  now  be  calculated.  With  the  same  data  and  calculations  given  in 
Question  169  and  its  answer,  we  will  have  a centrifugal  force  of  14,660 
lbs.,  which  must  be  exerted  at  the  beginning  of  the  stroke  to  accelerate 
the  piston.  The  influence  of  a connecting-rod  seven  times  the  length  of 
the  crank  will  increase  this  force  one-seventh,  as  explained  in  answer  to 
Question  174,  so  that  it  will  be  equal  to 

14,660  + 2,094  = 16,754  lbs. 

At  the  end  of  the  stroke  the  force  which  will  be  exerted  by  the  momen- 
tum of  the  reciprocating  parts  will  be 

14,660—  2,094  = 12,566  lbs. 

If,  now,  we  divide  these  forces  by  the  area  of  the  piston  (which  is  17 


358 


Catechism  of  the  Locomotive. 


inches  in  diameter)  = 227  square  inches,  and  it  will  give  73.8  and  55.3  lbs. 
as  the  pressure  per  square  inch  which  must  be  exerted  at  the  beginning 
and  end  of  the  stroke  to  start  and  stop  the  piston.  A distance,  E H=  73.8, 
should  then  be  laid  off  on  the  perpendicular,  E N,  below  the  atmospheric 
line,  E E,  and  a distance,  E D — 55.3  lbs.,  above  the  atmospheric  line. 
The  point  at  which  there  is  neither  acceleration  nor  retardation  of  the  pis- 
ton is  where  the  centre  lines  of  the  crank  and  of  the  connecting-rod  are 


at  right  angles.  This  is  the  case  where  the  piston  is  still  one  inch  ahead 
of  the  middle  of  its  stroke,  or  has  moved  11  inches.  If,  now,  we  mark 
this  point,  g,  on  the  atmospheric  line,  E F,  and  draw  the  arc  of  a circle, 
H g E*  through  the  three  points  which  have  been  laid  down,  the  vertical 
distance  of  this  line,  below  E E,  will  indicate  the  pressure  per  square  inch 


* This  curve  is  not  exactly  an  arc  of  a circle,  but  such  an  arc  is  a sufficiently  close  approxi- 
mation to  the  actual  curve  for  the  present  purpose. 


Action  of  the  Pistons,  Cranks  and  Driving-Wheels.  359 

at  each  point  of  the  stroke  which  must  be  exerted  on  the  piston  at  the 
speed  named  to  accelerate  it,  and  the  distance  of  g D,  above  E F,  the 
pressure  required  to  retard  the  piston.  In  other  words,  the  vertical  dis- 
tance of  H g below  the  atmospheric  line,  E E,  represents  the  pressure  on 
the  piston  which  is  needed  to  move  the  reciprocating  parts  alone  during 
the  first  part  of  the  stroke,  and  the  vertical  distance  of  g D,  above  E F, 
shows  the  pressure  which  the  momentum  of  these  parts  will  exert  on  the 
crank-pin  during  the  last  half  of  the  stroke,  or  the  force  which  must  be 
exerted  to  bring  them  to  a state  of  rest.  If  we  take  the  vertical  distances, 
HA,  bV  c 2' , d 3',  etc.,  from  fig.  291,  in  which  they  represent  the  net 
pressure  on  the  piston,  and  lay  them  off  on  the  vertical  lines  above  and 
from  the  curved  line,  H g D,  fig.  300,  and  draw  a curve,  ABC f,  through 
their  extremities,  then  the  vertical  distance  of  this  curve  above  the 
atmospheric  line,  E F,  will  represent  the  net  effective  pressure  which  is 
exerted  on  the  crank-pin.  It  has  been  explained  that  the  distance  of  the 
curve,  H g,  below  Eg,  represents  the  pressure  required  to  move  the  recip- 
rocating parts  alone,  and  therefore  it  must  be  deducted  from  the  total 
steam  pressure  on  the  piston  to  get  that  which  is  exerted  on  the  crank- 
pin.  Consequently  the  distances  1 V,  2 2',  3 3',  etc.,  above  E D,  represent 
the  pressure  on  the  crank-pin  during  the  first  portion  of  the  stroke.  As 
the  momentum  of  the  piston  exerts  pressure  on  the  crank-pin  during  the 
latter  half  of  the  stroke — which  is  represented  by  the  vertical  distance  of 
g D,  above  g F — therefore  the  steam  pressure  on  the  piston  must  be 
added  to  this  momentum  and  the  pressure  represented  by  the  distances, 
m 12',  n 13',  o 14',  etc.,  of  fig.  291,  are  laid  off  above  and  from  the  curve, 
g D,  fig.  300,  and  are  indicated  by  the  same  letters  and  numbers  in  both 
figures.  The  pressure  exerted  on  the  crank-pin  during  the  latter  part  of 
the  stroke,  therefore,  is  equal  to  that  of  the  steam  acting  on  the  piston 
added  to  the  momentum  of  the  piston,  and  is  represented  in  fig.  300  by 
the  vertical  distances,  12  12',  13  13',  14  14',  etc. 

The  back  pressure  on  the  piston  indicated  by  the  area  shaded  black,  in 
fig.  291,  is  laid  off  below  the  line,  g D,  fig.  300,  and  is  deducted  from  the 
momentum  of  the  piston. 

Thus,  at  23  inches  of  the  stroke  this  pressure  is  measured  by  the  line, 
23'  x,  fig.  291.  This  distance  is  therefore  laid  off  below  the  line,  g D>  fig- 
300,  and  is  indicated  by  the  same  number  and  letter  as  in  fig.  291.  The 
pressure  represented  by  the  distance,  D H',  of  fig.  291,  is  laid  off  in  the 
same  way  on  fig.  300.  By  extending  the  curve,  A B C f,  through  x and 
H’ , its  distance  above  the  line,  E F,  will  then  represent  the  pressure  on 


360 


Catechism  of  the  Locomotive. 


the  crank-pin  during  the  whole  of  the  backward  stroke,  and  its  distance 
below g F,  the  back  pressure  exerted  on  the  pin. 

The  length,  a A,  b 1',  c 2',  etc.,  of  the  vertical  lines  in  the  shaded  area, 
H E A B Cf,  fig.  300,  represents  the  steam  pressure  in  pounds  per  square 
inch  on  the  piston.  Their  length,  a 0,  b 1,  c 2,  etc.,  in  the  area,  H E g, 
represents  in  the  same  way  the  portion  of  the  pressure  which  must  be 
exerted  on  the  piston  to  move  and  accelerate  the  reciprocating  parts  from 
the  beginning  to  the  middle  of  the  stroke.  The  area,  g D F,  represents 
the  horizontal  pressure  exerted  by  the  reciprocating  parts  during  the  last 
half  of  the  stroke.  The  area,/- D H\  shows  the  net  back  pressure* on  the 
piston  near  the  end  of  its  stroke,^  f h,  the  net  effective  pressure  exerted 
by  the  momentum  of  the  reciprocating  parts  during  the  last  half  of  the 
stroke,  and  the  area,  E A B C f F,  above  the  horizontal  line,  E F,  shows 
the  net  effective  horizontal  pressure  exerted  on  the  crank-pin.  A similar 
diagram  has  been  made  for  the  forward  stroke  of  the  piston,  but  has  been 
laid  off  below  the  lines,  E g F,  and  H g D,  and  is  represented  by  the 
dotted  line,  H'  I J K E. 

Question  432.  In  what  way  does  the  momentum  of  the  reciprocating 
parts  modify  the  effect  of  the  pressure  of  the  steam  when  it  is  worked  expan- 
sively ? 

Answer.  It  equalizes  the  pressure  on  the  crank-pin  during  the  early 
and  latter  part  of  the  stroke.  This  will  be  seen  if  the  diagram,  figs.  291 
and  300,  are  compared.  Fig.  291  shows  that  the  steam  pressure  on  the 
piston  during  the  early  part  of  the  stroke  is  much  greater  than  during  the 
latter  part,  whereas  the  effect  of  the  reciprocating  parts,  as  shown  in  fig. 
300,  is  to  reduce  the  pressure  on  the  crank-pin  in  the  first  half  of  the 
stroke  and  increase  it  in  the  last  half. 

Question  433.  What  is  meant  by  the  rotative  effect  of  the  steam  on  the 
crank? 

Answer.  It  is  the  pressure  which  the  steam  exerts  at  right  angles  to 
the  centre  line  of  the  crank,  the  direct  effect  of  which  is  to  turn  the 
crank. 

Question  434.  How  can  the  rotative  effect  of  the  pressure  on  the  crank- 
pin  be  ascertained  ? 

Answer.  This  can  be  done  by  first  constructing  a diagram  similar  to 
fig.  300  for  any  given  speed,  point  of  cut-off,  pressure  of  steam,  or  dimen- 
sions of  engine.  Then  let  A B,  fig.  301,  represent  a horizontal  centre  line 
drawn  through  the  centre  of  the  cylinder  and  centre,  O,  of  the  axle. 
From  O as  a centre  draw  a circle,  O'  L B K,  whose  diameter  is  equal  to 


Action  of  the  Pistons,  Cranks,  and  Driving-Wheels.  361 


the  stroke  of  the  piston,  to  represent  the  path  of  the  centre  of  the  crank- 
pin.  From  the  front  dead-point,  o',  with  a distance  equal  to  the  connect- 
ing-rod, lay  off  the  mark.  A,  on  A B,  which  will  be  the  position  of  the 
centre  of  the  cross-head  pin  at  the  beginning  of  the  stroke.  Now,  for 
any  position  of  the  crank-pin,  such  as  C as  a centre,  and  with  the  length 
of  the  connecting-rod  as  a radius,  describe  a short  arc,  a,  intersecting  the 
line,  A B.  Then  the  distance,  A a , will  be  equal  to  the  movement  of  the 
cross-head  pin,  which  is  equal  to  that  of  the  piston  from  the  beginning  of 
the  stroke.  Then  draw  a C to  represent  the  centre  line  of  the  connect- 
ing-rod when  the  piston  has  moved  the  distance,  A a.  From  a,  a dis- 
tance, a b , should  be  laid  off  equal  to  the  horizontal  pressure,  in  pounds 


Diagrams  Showing  Rotation  Effect  on  Crank-Pin.  Scale  % in.=l  ft. 


per  square  inch,  exerted  by  the  combined  action  of  the  steam  pressure 
and  momentum  of  the  reciprocating  parts.  Now,  if  this  pressure  is 
exerted  against  the  end  of  the  connecting-rod,  a C,  which  at  this  point 
of  the  stroke  is  inclined  to  the  centre  line,  A B,  its  inclination  will  cause 
an  upward  verticle  pressure  to  be  exerted  at  a,  which  must  be  resisted  by 
the  guides.  If,  then,  a b is  drawn  equal  to  the  horizontal  force,  and  b c 
parallel  to  the  vertical  line,  a d,  and  if  from  the  intersection,  c , of  b c,  with 
a C,  a.  line,  d c,  is  drawn  parallel  to  a b,  we  will  have  a parallelogram,  a b c 
d,  of  which  the  centre  line,  a c,  of  the  connecting-rod  forms  a diagonal, 
and  the  side,  a b,  being  equal  to  the  horizontal  force,  b c , will  be  equal  to 


862 


Catechism  of  the  Locomotive. 


the  vertical  pressure,  and  a c will  represent  the  pressure  exerted  in  the 
direction  of  the  centre  line  of  the  connecting-rod. 

To  ascertain  the  pressure  exerted  on  the  crank-pin,  it  is  a little  more 
convenient  to  draw  a horizontal  line,  C D,  through  the  centre  of  the 
crank-pin  and  parallel  with  A B.  Then  from  C lay  off  C e , equal  to  the 
horizontal  pressure,  and  draw  the  vertical  line  e f,  then  f C will  be  the 
pressure  exerted  by  the  connecting-rod  in  the  direction,  a C,  of  its  centre 
line.  To  determine  the  pressure  that  is  exerted  in  the  direction,  g C,  at 
right  angles  to  the  crank,  C O,  the  force,  f C,  may  be  resolved  into  two 
components,  one  acting  in  the  direction,  C,  at  right  angles  to  the  crank, 
and  the  other  in  the  direction  of  C O,  of  its  centre  line.  If  we  extend  C 
O to  h , and  from  /,  the  end  of  f C,  we  draw  f g parallel  to  O h,  the  centre 
line  of  the  crank,  and  from  the  centre,  C,  draw  Cg,  at  the  right  angles  to 
C O,  and  complete  the  parallelogram,/^  C h , then  we  have  a parallelo- 
gram of  which  the  diagonal  represents  the  magnitude  and  direction  of 
the  force  acting  through  the  connecting-rod,  and  the  sides  are  parallel  to 
the  direction  into  which  we  want  to  resolve  this  force.  Therefore,^  C 
represents  the  force  exerted  by  f C,  at  right  angles  to  the  crank,  and  h C 
that  in  the  direction  of  its  centre  line. 

If  the  crank  is  in  the  position  shown  by  the  dotted  lines  at  C',  and  the 
pressure  of  the  connecting-rod  is  exerted  on  the  crank-pin  in  the  direction 
of  the  arrow,  r,  then  the  rotative  effect  can  be  ascertained  in  a similar  way 
to  that  already  described — the  horizontal  line,  (TV,  equal  to  the  horizontal 
pressure,  is  drawn  through  the  centre  of  the  crank-pin,  and  the  centre 
line,  b C , of  the  connecting-rod  is  extended  to /'.  A perpendicular,  e’  f , 
is  then  drawn  from  /'  through  e’ , and  C'  f is  equal  to  the  pressure  of  the 
connecting-rod  on  the  crank-pin.  A line,  C' g',  is  drawn  perpendicular  to 
the  centre  line,  C'  O,  of  the  crank,  and  through  C'  and /',  lines  C'  h'  and 
f'g'  are  drawn  parallel  to  the  crank,  and  from  f f'h'  is  drawn  parallel  to 
C'  g’.  We  then  have  the  parallelogram,  C'  h'  f g’,  of  which  C'  g'  or  h'  f' 
represents  the  rotative  effect. 

Question  435.  In  what  other  way  may  we  ascertain  the  pressure  exerted 
at  right  angles  to  the  crank , or  the  rotative  effect  ? 

Answer.  It  can  be  shown  that  if  the  crank  and  connecting-rod  are 
drawn  for  any  position  of  the  piston,  as  in  fig.  301,  that  if  the  line,  e C, 
representing  the  horizontal  pressure  exerted  on  the  piston,  is  made  equal 
to  the  length,  O C,  of  the  crank,  and  if  the  centre  line,  a C,  of  the  con- 
necting-rod is  extended  so  as  to  intersect  a vertical  line,  O K,  drawn 
through  the  centre,  O,  of  the  axle,  that  the  distance,  O m , will  then  repre- 


Action  of  the  Pistons,  Cranks,  and  Driving-Wheels. 


363 


sent  the  pressure  exerted  at  right  angles  to  the  crank.*  If,  then,  we 
MULTIPLY  THE  PRESSURE  ON  THE  PISTON  BY  THE  DISTANCE  ( O M or 
O n\  fig.  801)  FROM  THE  CENTRE  OF  THE  AXLE,  AT  WHICH  THE  CENTRE 
LINE  OF  THE  CONNECTING-ROD  INTERSECTS,  A VERTICAL  LINE  DRAWN 
THROUGH  THE  CENTRE  OF  THE  AXLE,  AND  DIVIDE  BY  THE  LENGTH 
OF  THE  CRANK,  IT  WILL  GIVE  THE  ROTATIVE  EFFECT.  When  the  Crank 
is  back  of  the  centre  of  the  axle,  as  at  C' , it  is  not  necessary  to  extend  the 
centre  line  of  the  connecting-rod  as  it  intersects  the  vertical  line,  as  at  n\ 
without  being  extended. 

Question  436.  How  may  the  rotative  effect  be  shown  for  a whole 
revolution  of  the  driving-wheel  ? 

Answer.  To  do  this  a circle,  LI  K B,  fig.  302,  is  drawn  to  represent 
the  path  of  the  centre  of  the  crank-pin,  and  a horizontal  centre  line,  A B, 
as  described.  Now  divide  the  circle  into  12  equal  divisions — 1 2 3 4,  etc. 
From  the  dead-points,  1 and  7,  with  the  length  of  the  connecting-rod  as  a 
radius,  mark  V and  7'  on  A B ; these  will  represent  the  two  ends  of  the 
piston’s  stroke.  Now,  from  2 as  a centre,  and  with  the  length  of  the  con- 
necting-rod, intersect  A B,  at  2',  with  a short  arc,  and  draw  2'  2 m.  Then 
V 2'  will  represent  the  distance  that  the  piston  has  moved  while  the  crank 
has  turned  from  1 to  2,  or  one-twelfth  of  its  revolution.  In  a similar  way 
3 3',  7 7',  8 8',  9 9',  can  be  laid  down,  which  will  give  us  the  movement  of 
the  piston  for  successive  twelfths  of  the  first  and  third  quarters  of  a 

* It  is  not  easy  to  prove  this  without  the  aid  of  mathematics.  Those  who  know  a little  of 
geometry  will  be  able  to  understand  the  following  demonstration,  those  who  do  not  must 
accept  the  conclusions  without  understanding  the  proof : In  fig.  301,  e C,  which  represents  the 
pressure  per  square  inch  on  the  piston,  has  been  made  equal  to  the  radius,  C O,  of  the  crank, 
and  as  explained  above,  f C represents  the  pressure  exerted  through  the  connecting-rod  on  the 
crank.  If  the  connecting-rod  was  infinitely  long,  the  leverage  with  which  it  would  act  on  the 
crank  would  be  equal  to  the  vertical  distance,  C ny  of  the  centre  of  the  crank-pin,  from  the  line, 
A B , and  the  rotative  effect  would  be  equal  to  the  pressure  on  the  piston  multiplied  by  C n. 
But  owing  to  the  angularity  of  the  connecting-rod,  the  leverage  through  which  it  acts  on  the 
crank  is  equal  to  O jt,  a line  drawn  through  the  centre,  O , of  the  axle  and  perpendicular,  to 
a C in.  So  that  if  R , the  length  of  the  crank,  is  assumed  to  be  equal  to  1,  the  rotative  effect  is 
equal  to  the  pressure,/ C,  exerted  through  the  connecting-rod,  multiplied  by  O x.  As  the  two 
triangles,  Cfe  and  O x m are  similar, 

Ox:  O mi:Ce  : C/y 
so  that  O in  x C e — O x x Cf. 

As  C e.  which  represents  the  horizontal  pressure  of  the  piston  and  reciprocating  parts,  has 
been  made  equal  to  C O or  R , the  radius  of  the  crank,  we  have 

OmXR  = OxXCf% 

that  is,  the  horizontal  pressure  of  the  piston  and  reciprocating  parts  multiplied  by  O in  is  equal 
to  the  rotative  effect.  A similar  demonstration  will  prove  that  O n'  x R will  be  equal  to  the 
rotative  effect  when  the  crank-pin  is  in  the  position  C' . 


364 


Catechism  of  the  Locomotive. 


revolution.  To  avoid  confusion  in  the  diagram,  the  position  of  the  con- 
necting-rod has  not  been  laid  out  for  the  second  and  fourth  quarters  of 
the  revolution,  and  also  because  the  positions  of  the  crank-pin  and  piston 
are  the  same  during  the  first  and  fourth  and  the  second  and  third  quarters 
of  the  revolution. 

Next  draw  a horizontal  line,  C D,  fig.  303,  equal  in  length  to  the  cir- 
cumference of  the  driving-wheel,  and  subdivide  this  line  into  twelve  equal 
divisions — V"  2'”  3"'  4"'  5'"  6'",  etc.  From  these  points  of  division  draw 
perpendiculars,  V"  1,  2"'  2,  3"'  3,  etc.  Draw  the  horizontal  line,  1 O,  above 
C D,  so  that  1 V"  and  O O'"  are  equal  to  half  the  diameter  of  the  wheel. 
Then,  from  1 as  a centre,  and  with  1 V"  as  a radius,  describe  a circle,  A B 
C,  to  represent  the  driving-wheel,  and  from  1 lay  off  the  crank-pin,  1',  in 
the  first  position  shown  in  fig.  302.  As  this  is  the  dead-point,  the  pressure 
of  the  piston  exerts  no  rotative  effect  on  the  crank.  From  2 draw  another 
circle  and  lay  off  the  crank-pin,  2',  in  the  second  position  shown  in  fig.  302. 
As  C D has  been  made  equal  in  length  to  the  circumference  of  the  wheel, 
and  it  has  been  divided  into  twelve  equal  parts,  V"  2"'  is  equal  to  one-twelfth 
of  the  circumference,  so  that  the  wheel,  ABC,  in  turning  one-twelfth  of  a 
revolution  would  roll  from  V"  to  2f".  From  2 as  a centre,  we  then  draw 
another  circle  to  represent  the  wheel  when  it  has  turned  one-twelfth  of  a 
turn  and  has  rolled  from  1 to  2.  The  crank  is  then  in  the  position  shown 
at  2'  in  fig.  302,  and  the  piston  has  moved  1{:J  inches.  By  drawing  2' m to 
represent  the  connecting-rod,  we  find  that  2 m is  equal  to  6f  inches.  It  will 
be  supposed  now  that  the  engine  is  running  at  a speed  of  only  four  miles 
an  hour,  and  that  there  is  a uniform  pressure  of  140  lbs.  on  the  piston,  as 
shown  by  the  diagram,  fig.  285.  At  this  slow  speed  the  power  required  to 
accelerate  and  retard  the  reciprocating  parts  is  so  little  that  it  may  be 
disregarded. 

To  get  the  rotative  effect  for  the  position  of  the  crank  shown  at  2 2', 
fig.  303,  we  must  then  multiply  140  x 6f =945,  and  divide  by  12,  which 
gives  78.7  as  the  rotative  effect  in  pounds  pressure  per  square  inch  of  the 
piston.  The  spaces  between  the  horizontal  lines,  below  C D,  are  supposed 
each  to  represent  10  lbs.  pressure  per  square  inch,  as  indicated  by  the 
figures  on  the  left  hand  side  of  fig.  303,  and  the  pressure  which  has  been 
calculated  can  be  laid  off  from  2"'  to  E.  Proceeding  in  the  same  way  for 
the  third  position,  3 3',  of  the  crank,  we  find  that  the  piston  has  moved 
6-f  inches,  as  shown  in  fig.  302,  and  3 m is  equal  to  Hi  inches. 

Therefore,  140  x lli 

=129.8. 


12 


Fig.  303.  Diagram  Showing  Rotative  Effect  on  Crank-Pin  Scale  % in.=l  ft. 


366 


Catechism  of  the  Locomotive. 


This  pressure  is  laid  off  from  the  line,  C D,  fig.  303,  on  the  perpendicu- 
lar, 3"'  F.  In  the  same  way  the  rotative  effect  is  calculated  and  laid  down 
in  fig.  303,  for  each  of  the  successive  positions,  4 5 6 7,  etc.,  of  the  crank, 
shown  in  fig.  302,  and  curves,  C E F G'  H I J and  J K L M'  N P D,  fig. 
303,  are  drawn  through  the  points  laid  down  On  the  perpendicular  lines. 
The  vertical  distance  of  these  curves,  below  C D , then  represents  the  rota- 
tive effect  which  is  exerted  by  one  crank  at  each  point  during  a complete 
revolution  of  the  driving-wheel. 

But  while  the  pressure  on  the  piston  on  one  side  of  the  locomotive  is 
acting  on  its  crank,  there  is  a simultaneous  action  on  the  other  crank, 
which  stands  at  right  angles  to  the  first  one,  and  whose  successive  posi- 
tions is  shown  by  the  dotted  lines,  1 1",  2 2",  3 3",  etc.  The  rotative  effect 
acting  on  the  wheels  is  therefore  equal  to  that  exerted  on  each  of  the 
cranks  added  together.  To  show  this  combined  effect,  then,  we  must  lay 
off  other  curves  from  those  already  drawn.  Thus,  the  opposite  crank. 
1 1",  in  the  first  position  of  the  wheels  stands  at  right  angles  to  the  centre, 
line,  11',  and  O m,  is  then  equal  to  12  inches,  so  that  we  have 

140  x 12 
= 140. 

12 

Therefore  140  is. laid  down  from  Y"  to  C'  on  the  vertical  line,  Y"  Y'". 
A similar  calculation  is  made  for  the  rotative  effect  of  the  crank,  2 2",  in 
the  second  position,  and  as  the  action  of  the  opposite  crank  exerts  addi- 
tional rotative  effect  on  the  wheel,  this  force  is  added  to  that  of  the  first 
crank  by  laying  it  off  from  E to  E . Proceeding  in  the  same  way  for  the 
other  position  of  the  crank,  and  laying  off  the  distances,  F F',  H H' , etc., 
and  drawing  the  curve,  C'  E'  F'  G'  H' — D\  through  the  points  thus  laid 
down,  we  have  a curve  whose  distance  below  the  line,  C D,  represents  the 
combined  rotative  effect  exerted  by  the  pressure  in  the  two  cylinders 
during  a whole  revolution. 

QUESTION  437.  What  peculiarity  may  be  observed  in  the  form  of  this 
curve? 

Answer.  It  will  be  seen  that  the  rotative  effect  varies  very  much  at 
different  points  of  the  revolution.  It  is  greatest  when  the  wheel  is  mid- 
way between  the  positions  11  and  12,  when  the  two  cranks  are  in  front  of 
the  axle  and  stand  at  angles  of  45°  with  horizontal  or  perpendicular  lines. 
When  the  wheel  is  between  the  2 and  3 and  8 and  9 positions,  or  when 
the  cranks  both  again  stand  at  angles  of  45°  with  a horizontal  line,  the 


Action  of  the  Pistons,  Cranks,  and  Driving-Wheels.  367 

rotative  effect  is  equal,  though  somewhat  less  than  it  is  when  the  cranks 
are  both  in  front  of  the  axle.  Between  the  5th  and  6th  positions  of  the 
wheel,  when  the  cranks  are  both  behind  the  axle  and  at  the  angles  of 
54°  to  a horizontal  line,  the  rotative  effect  is  less  than  at  any  of  the  other 
high  points. 

Question  438.  How  may  this  peculiarity  of  the  variation  in  the  rota- 
tive effect  be  explained? 

Answer.  It  is  due  to  the  fact  that  when  both  cranks  are  in  front  of  the 
axle,  the  effect  of  the  angularity  of  both  connecting-rods  is  to  increase  the 
rotative  effect.  When  one  crank  is  in  front  and  the  other  behind  the  axle, 
the  one  connecting-rod  increases  and  the  other  diminishes  the  rotative 
effect,  and  when  the  two  cranks  are  behind  the  axle,  both  rods  diminish 
the  rotative  effect. 

Question  439.  At  what  points  in  a revolution  is  the  least  rotative 
effect  exerted? 

Ajiswer.  When  one  of  the  two  cranks  is  at  a dead  point,  that  is,  in  the 
1st,  4th,  7th  and  10th  positions,  shown  in  fig.  303.  If  the  steam  pressure 
is  the  same,  the  rotative  effect  is  equal  in  each  of  these  positions  of  the 
cranks. 

Question  440.  When  the  rotative  effect  is  represented  in  powids  pres- 
sure per  square  inch  of  piston,  as  in  fig.  joj,  how  can  we  know  the  actual 
rotative  effect  or  the  tractive  force  exerted  at  the  cir  conference  of  the  wheel? 

Answer.  This  can  be  done  by  simply  measuring  the  vertical  distances 
of  the  curve  with  a different  scale.  Thus,  in  fig.  303,  the  spaces  between 
the  horizontal  lines  below  C D have  been  supposed  to  represent  10  lbs. 
pressure  on  each  square  inch  of  the  piston,  as  indicated  by  the  figures  on 
the  left-hand  side.  If  the  piston  is  17  inches  in  diameter,  its  area  would 
be  very  nearly  227  square  inches.  Ten  pounds’  pressure  would  therefore 
exert  a total  pressure  of  2,270  lbs.  on  the  piston.  If  the  wheel  is  5 feet  in 
diameter  and  the  stroke  2 feet,  the  pressure  on  the  piston  would  be 
exerted  with  a leverage  of  2 to  5,  so  that  the  actual  tractive  force  would  be 
2,270  x 2 

= 908  lbs. 

5 

for  each  ten  pounds  of  pressure.  If,  then,  we  suppose  the  spaces  between 
the  horizontal  lines  each  represent  908  lbs.,  as  indicated  by  the  figures  on 
the  right-hand  side,  we  can  measure  the  actual  tractive  force  exerted  at 
the  circumference  of  the  wheel. 

Question  441.  How  can  we  lay  off  curves  to  represent  the  rotative 


Effect  on  Crank-Pin.  Scale  % in.=l  ft. 


Action  of  the  Pistons,  Cranks,  and  Driving-Wheels.  369 

effect  when  the  pressure  in  the  cylinder  is  not  uniform  during  the  stroke , 
and  when  the  speed  is  so  high  that  the  acceleration  and  retardation  of  the 
reciprocating  parts  has  an  importa7it  influence  on  the  action  of  the  engine  ? 

Answer.  To  do  this  a diagram,  fig.  304,  similar  to  fig.  303,  should  be 
laid  down.  For  each  position  of  the  crank  we  must  ascertain  the  move- 
ment of  the  piston.  Then  construct  a diagram  like  that  represented  by 
fig.  300,  and  from  that  take  the  net  horizontal  pressure  exerted  on  the 
crank  when  the  piston  is  in  the  position  indicated.  Thus  when  the  crank 
is  in  the  second  position  represented  in  figs.  302  and  304,  it  has  turned 
one-twelfth  of  a revolution,  and  the  crank  has  moved  1||  inch.  From 
the  diagram,  fig.  300,  we  find  that  the  pressure  at  1||  inch  of  the  stroke 
measured  above  the  line,  EF,  is  65  lbs.  As  O m is  equal  to  6f  inches,  we 
have  for  the  calculation,  55  x gj 

= 36.5. 

12 

We  therefore  lay  off  36.5  from  2'"  to  E,  in  fig.  304.  In  the  third  position 
of  the  crank  the  piston  has  moved  6f  inches ; the  pressure  is  then  90  lbs., 
and  2 in  is  equal  to  114,  so  that  the  rotative  effect  is  equal  to  83.4  lbs., 
which  distance  is  laid  off  from  3'"  to  F.  Similar  calculations  are  made 
for  other  positions  of  the  crank,  the  steam  pressure  being  taken  from  fig. 
300,  and  the  curves,  C E F G — D,  and  C'  E'  F'  G — D',  are  drawn  in  the 
manner  described.  The  latter  curve  then  represents  the  rotative  effect 
when  cutting  off  steam  at  one-third  of  the  stroke  and  at  a speed  of  50 
miles  per  hour. 

Question  442.  What  is  the  effect  of  working  steam  expansively  at 
high  speeds  ? 

Answer.  As  already  pointed  out,  the  effect  of  cutting  off  steam  early 
in  the  stroke,  and  the  influence  of  the  reciprocating  parts  tend  to  equalize 
the  rotative  effect  during  the  whole  revolution  of  the  wheel.  This  is 
shown  by  the  curve  C'  E'  F'  G — D\  which  shows  that  the  rotative  effect 
on  the  crank-pin  does  not  vary  nearly  as  much  as  the  corresponding  curve 
in  fig.  303  shows  that  it  does  when  the  steam  is  not  expanded  and  when 
the  reciprocating  parts  move  slowly.  There  is  also  considerable  irregu- 
larity in  the  curves  in  fig.  304,  which  is  produced  by  the  various  and  com- 
plicated causes  which  determine  its  form.  The  black  areas,  at  G and  /, 
represent  the  back  pressure  on  the  piston,  shown  also  at  F,  in  fig.  300. 
The  curved  dotted  line  drawn  through  the  centres  of  the  crank-pin,  in  figs. 
303  and  304,  show  the  path  in  which  the  pin  moves  during  one  revolution 
of  the  wheel. 


CHAPTER  XVIII. 


ADHESION  AND  TRACTION. 

QUESTION  443.  What  is  meant  by  the  “ adhesion  " of  a locomotive. 

Answer.  It  is  the  resistance  which  prevents  or  opposes  the  slipping  of 
the  driving-wheels  on  the  rails,  and  is  due  to  the  friction  of  the  former  on 
the  latter. 

Question  444.  On  what  does  the  amount  of  this  friction  depend? 

Answer.  It  depends  upon  the  weight  or  pressure  of  the  surfaces  in 
contact,  and  consequently  upon  the  load  which  rests  on  each  wheel.  It 


A 


Fig.  305.  Diagram  Showing  Adhesion  of  Locomotive.  Scale  in.=l  ft. 


also  depends  upon  the  condition  of  the  rails,  and  probably  to  some  extent 
upon  the  material  of  which  they  and  the  tires  on  the  wheels  are  made, 
and  to  the  amount  of  surfaces  in  contact. 

Question  445.  How  much  force  is  required  to  make  the  driving-wheels 
of  a locomotive  slip  on  an  ordinary  railroad  track  ? 

Answer.  The  force  required  to  make  them  slip  will,  as  already  stated, 


Adhesion  and  Traction. 


371 


vary  very  much  with  the  condition  of  the  rails.  If  they  are  quite  dry  and 
clean  it  will  require  a force  equal  to  about  one-fourth  the  weight  on  the 
wheels.  That  is,  supposing  we  have  a wheel,  A B,  fig.  305,  attached  to  a 
frame  which  is  fastened  so  that  it  cannot  move,  and  that  the  wheel  rests 
on  a rail  and  is  loaded  with  say  12,000  lbs.,  if  now  a rope  or  chain  could 
be  attached  at  a point,  B,  exactly  at  the  tread  of  the  wheel,  and  carried 
over  a pulley,  C,  then  it  would  require  a weight,  D,  of  about  3,000  lbs. 
attached  to  the  end  of  the  rope  to  make  the  wheel  slip.  If  the  rails  were 
sanded,  the  adhesion  would  be  somewhat  greater,  and  if  they  were  wet 
or  muddy  or  greasy,  considerably  less.  The  proportion  of  the  adhesion  to 
the  weight  in  the  driving-wheels  is  about  as  follows : 

On  dry-sanded  rails  it  is  equal  to  one-third. 

On  perfectly  dry  rails,  without  sand,  it  is  one-fourth. 

Under  ordinary  conditions,  without  sand,  or  on  wet-sanded 

RAILS,  ONE-FIFTH. 

On  wet  or  frosty  rails,  one-sixth. 

With  snow  or  ice  on  the  rails,  the  adhesion  is  still  less. 

Of  course  the  total  weight  oh  all  the  driving-wheels  must  be  taken  in 
calculating  the  adhesion.  Thus,  if  a locomotive  has  four  driving-wheels, 
and  each  one  of  them  bears  a load  of  12,000  lbs.,  then  the  total  weight  on 
the  driving-wheels,  or  adhesive  weight,  as  it  is  called,  will  be  12,000  x4  = 
48,000  lbs.,  and  the  adhesion  will  be 

48,000 

= 9,600  lbs. 

5 

Question  446.  What  is  meant  by  the  tractive  power  of  a locomotive? 

Answer.  It  is  the  force  with  which  the  locomotive  is  urged  in  a hori- 
zontal direction  by  the  pressure  of  the  steam  in  the  cylinders,  and  which 
therefore  tends  to  move  the  locomotive  and  draw  the  load  attached  to  it. 

The  tractive  power  is  due  to  the  effective  pressure  of  steam  on  the  pis- 
tons, and  therefore  its  amount  is  dependent  upon  the  average  steam 
pressure  in  the  cylinders  on  the  area  of  the  piston,  and  also  on  the  dis- 
tance through  which  the  pressure  is  exerted,  or,  in  other  words,  on  the 
stroke  of  the  piston  and  the  size  of  the  driving-wheels.  Thus,  if  we  have' 
a cylinder  17  inches  in  diameter  and  2 feet  stroke,  and  an  average  steam 
pressure  of  50  lbs.  per  square  inch,  then,  as  the  area  of  such  a piston 
would  be  227  square  inches,  the  average  pressure  on  it  would  be  227  x 50 
= 11,350  lbs.,  and  as  each  piston  moves  through  4 feet  during  one  revolu- 
tion of  the  wheels,  the  number  of  foot-pounds  of  energy  exerted  by  it 


372 


Catechism  of  the  Locomotive. 


would  be  11,350x4=45,400,  and  for  the  two  cylinders  of  a locomotive 
double  that  amount,  or  90,800  foot-pounds.  If  the  driving-wheels  are  5 
feet  in  diameter,  their  circumference  will  be  15.7  feet,  and  therefore  the 
locomotive  will  move  that  distance  on  the  rails  during  one  revolution,  if 
the  wheels  do  not  slip.  The  90,800  foot-pounds  of  energy  is  therefore 
exerted  through  a distance  of  15.7  feet,  and  therefore 

90,800 

= 5,783  lbs., 

15.7 

which  is  the  force  exerted  at  the  circumference  of  the  wheel  as  it  revolves 
and  the  locomotive  moves.  If  the  wheels  were  only  half  the  diameter,  or 
2-J-  feet,  then  their  circumference  would  be  7.85  feet,  and  the  tractive  power 
would  be  90,800 

- — — = 11,56G  lbs., 

7.85 

or  double  what  it  was  before.  It  will  be  seen,  then,  that  the  tractive  force 
of  a locomotive  is  dependent  upon  (1)  the  average  steam  pressure  in  the 
cylinders,  (2)  the  area  of  the  pistons,  (3)  the  stroke  of  the  pistons,  and  (4) 
the  diameter  of  the  driving-wheels. 

Question  447.  How  is  the  tractive  power  of  a locomotive  calculated? 

Answer.  By  multiplying  together  the  area  of  the  piston  in 

SQUARE  INCHES,  THE  AVERAGE  EFFECTIVE  STEAM  PRESSURE  IN  POUNDS 
PER  SQUARE  INCH  ON  THE  PISTON  DURING  THE  WHOLE  STROKE,  AND 
FOUR  TIMES  THE  LENGTH  OF  THE  STROKE  OF  THE  PISTON,*  AND  DI- 
VIDING THE  PRODUCT  BY  THE  CIRCUMFERENCE  OF  THE  WHEELS.  The 
result  will  be  the  tractive  power  exerted  in  pounds.  The  adhesion  must, 
of  course,  always  exceed  the  tractive  force,  otherwise  the  wheels  will  slip. 

Question  448.  How  is  the  locomotive  made  to  advance  by  causing  the 
wheels  to  revolve  ? 

Answer.  The  pressure  of  steam  in  the  cylinders  is  exerted  in  one  direc- 
tion against  the  piston,  and  in  the  opposite  direction  against  the  cylinder- 
head,  as  shown  in  fig.  305,  in  which  the  steam  is  represented  by  the  dotted 
shading  in  the  back  end  of  the  cylinder,  and  the  direction  of  the  pressure 
by  the  darts,  S S.  The  pressure  against  the  piston  is  communicated  by 
the  connecting-rod  to  the  crank-pin,  E,  and  that  on  the  cylinder-head  is 
exerted  against  the  axle  through  the  frame,  F F',  and  the  direction  of  the 
two  forces  is  indicated  by  the  two  darts,  a and  b.  We  may  now  regard 

* This  length  may  be  taken  in  feet,  inches,  or  any  other  measure,  but  in  making  the  calcula- 
tion the  circumference  of  the  wheels  must  be  taken  in  the  same  measure  as  the  stroke  of  the 
piston. 


Adhesion  and  Traction. 


373 


the  spokes  of  the  wheels  as  acting  as  levers,  and  assume  that  the  fulcrum 
is  either  at  the  centre,  G,  of  the  axle,  or  at  B , the  point  of  contact  of  the 
wheel  with  the  rail.*  It  may  be  assumed  that  it  is  at  the  centre,  G,  of  the 
axle,  and,  for  the  sake  of  even  figures,  that  the  wheel  is  6 feet  in  diameter, 
and  cylinders  have  2 feet  stroke.  It  will  also  be  supposed  that  the  engine 
is  supported,  so  that  the  wheels  do  not  touch  the  rails,  and  that  a chain  or 
rope  passing  over  a pulley,  C,  is  attached  to  the  wheels  at  B and  with  a 
weight  at  D.  We  now  have  a force,  a,  of  say  10,000  lbs.  exerted  on  the 
crank-pin,  or  at  the  end  of  the  short  arm,  E G,  of  the  lever,  E G B.  As 
EG  is  1 foot  and  G B is  3 feet  long,  10,000,  at  E,  would  be  balanced  by 
10,000  x 1 

= 3,333  lbs. 

3 

at  B.  In  other  words,  it  would  require  3,333  lbs.  suspended  from  the 
chain,  at  D,  to  resist  the  strain  at  E.  But  when  this  is  the  case,  the  pres- 
sure of  the  axle  at  the  fulcrum,  in  the  direction  of  the  dart,  c , is  equal  to 
the  pressure  against  the  crank-pin,  E,  in  the  opposite  direction,  and  indi- 
cated by  the  dart,  a.  We  thus  have  two  forces,  one  at  <2  = 10,000  lbs.,  and 
another  at  i?=3,333  lbs.,  both  in  a forward  direction.  Then  added  to- 
gether are  equal  to  10,000  + 3,333=13,333  lbs. 

As  the  pressure  against  the  axle  in  the  opposite  direction,  b , is  only 
10,000  lbs.,  there  will  be  an  unbalanced  force  of  3,333  lbs.  acting  in  the 
direction  of  the  dart,  c,  and  tending  to  move  it  that  way.  As  the  axle  is 
attached  to  the  locomotive  frame,  this  force  will,  of  course,  have  a ten- 
dency to  move  the  whole  machine,  and  is  really  the  tractive  force  of  the 
engine. 

If,  on  the  other  hand,  we  regard  the  point  of  contact,  B,  of  the  wheel 
with  the  rail  as  a fulcrum,  we  have  a force  of  10,000  lbs.  acting,  at  E, 
against  a lever,  E G Bt  4 feet  long.  The  force  which  this  would  exert 
against  the  axle,  G,  would  be  calculated  by  multiplying  10,000  by  the 
whole  length  of  the  lever,  and  dividing  by  its  long  arm, ^7  B,  so  that  we 
will  have  10,000x4 

= 13,333  lbs. 

3 


* The  question  whether  the  centre  of  the  axle  or  the  point  of  contact  with  the  rail  is  the  ful- 
crum of  the  lever  in  this  case  has  been  the  subject  of  much  discussion  and  contention.  As  the 
word  fulcrum  means  “ a point  about  which  a lever  moves,”  it  is  believed  that  the  dispute  is 
due  simply  to  a difference  in  the  meaning  assigned  to  the  word  fulcrum.  If  we  regard  the 
fulcrum  as  the  point  which  is  fixed  in  relation  to  the  locomotive,  then  it  is  at  the  centre  of  the 
axle  ; but  if  we  refer  it  to  the  surface  of  the  earth,  then  it  is  at  the  top  of  the  rail. 


374 


Catechism  of  the  Locomotive. 


exerted  at  G ; and  as  the  pressure  exerted  by  the  steam  in  the  cylinder  in 
the  direction  of  the  dart,  b . is  only  10,000,  there  would  be  an  unbalanced 
strain  of  13,333  — 10,000=3,333  lbs.  acting  against  the  axle  in  the  direc- 
tion of  the  dart,  c , or,  in  other  words,  there  is  3,333  lbs.  more  of  force 
pulling  the  axle  forward  than  there  is  pushing  it  backward. 

When  the  crank-pin  is  below  the  axle,  in  the  position  shown  in  fig.  306, 
then,  if  the  centre  of  the  axle  is  regarded  as  the  fulcrum,  we  have  a pres- 
sure of  10,000  lbs.  pushing  against  the  front  cylinder-head,  which  is  trans- 
ferred to  the  axle  by  the  frames,  and  acts  on  the  axle  in  the  direction  of 
the  dart,  c,  and  we  also  have  a pressure  acting  against  the  crank-pin,  E,  in 
the  direction  of  the  dart,  a . If  G is  the  fulcrum,  the  pressure  which  the 


A 


force  a—  10,000  lbs.  would  exert,  at  B , would  be  calculated  by  multiplying 
it  by  the  short  arm,  G E,  of  the  lever,  and  dividing,  by  G B,  its  whole 
length — that  is, 

10,000x1 

— 3,333  lbs., 

3 

which  is  the  tractive  force  exerted  at  B. 

If,  on  the  other  hand,  B is  the  fulcrum,  then  the  force  exerted  on  the 
axle,  G,  by  the  pressure  of  the  piston  on  the  crank-pin  would  be  calculated 


Adhesion  and  Traction. 


by  multiplying  it  by  the  length,  E B,  of  its  long  arm,  and  dividing  by  its 
whole  length,  G B,  or  10,000  x 2 

— = 6,667  lbs., 

3 

exerted  at  G in  the  direction  of  b.  But  the  pressure  on  the  cylinder- 
head  pulls  against  the  axle,  G,  in  the  direction,  c,  with  a force  of  10,000,  so 
that  the  excess  of  strain  in  the  direction,  c,  will  be  equal  to  10,000  — 6,667 
=3,333  lbs. 

It  will  be  seen,  then,  that  it  is  immaterial  which  point  is  regarded  as  the 
fulcrum,  as  the  result  of  the  calculations  is  exactly  the  same. 

It  must  not,  however,  be  hastily  supposed  from  what  has  been  said  that 
the  total  pressure  against  the  axle  can  be  greater  than  its  resistance  to 
the  pressure.  As  soon  as  the  one  exceeds  the  other,  it  will  move.  But 
supposing  that  it  requires  a force  equal  to  3,333  lbs.  to  draw  a train 
coupled  to  the  engine,  as  soon  as  the  difference  between  the  force  exerted 
against  the  axle  by  the  piston  to  move  it  forward  and  that  which  presses 
it  back  exceeds  3,333  lbs.,  the  locomotive  will  move  the  train.  If  the 
force  exerted  continues  to  exceed  the  resistance,  the  speed  of  the  train 
will  be  accelerated,  and  thus  the  resistance  which  holds  the  engine  back 
and  that  which  pushes  it  forward  will  always  be  equal. 

Question  449.  Does  the  fact  that  the  piston  is  working  from  the  end 
of  a long  lever,  E G B,  fig.  305,  when  the  crank-pin  is  above  the  axle , en- 
able the  loco7notive  to  start  a heavier  train  than  when  the  crank-pin  is 
below  the  axle  and  the  piston  is  working  against  a shorter  lever,  G E B, 
fig • 306? 

Answer.  No;  because  as  has  already  been  shown,  the  pressure  against 
the  axle  is  the  same  in  both  cases.  It  is,  in  fact,  only  during  the  forward 
stroke  that  the  pressure  on  the  crank-pin  moves  the  engine  forward. 
The  forward  pressure  which  is  exerted  by  the  crank-pin  at  the  axle  is 
then  greater  than  that  exerted  against  the  latter  in  the  opposite  direction 
by  the  cylinder-heads  and  frames.  It  is  this  excess  of  crank  pressure 
which  moves  the  engine  and  which  is  the  tractive  force  during  the  for- 
ward stroke.  During  the  backward  stroke  the  piston  is  pushing  the  axle 
backward,  and  the  pressure  against  the  front  cylinder-head  is  pulling  it 
forward.  The  latter  then  exceeds  the  former,  and  the  difference  between 
the  two  is  the  force  which  moves  the  engine  forward.  As  has  been  shown, 
the  difference  is  the  same  in  both  positions  of  the  crank,  and  therefore 
the  locomotive  cannot  from  this  cause  pull  more  when  the  crank  is 
above  the  axle  than  when  it  is  below. 


CHAPTER  XIX. 


INTERNAL  DISTURBING  FORCES  IN  THE  LOCOMOTIVE. 

Question  450.  What  are  the  internal  disturbing forces  in  a locomotive  ? 

Answer.  They  are:  1,  those  produced  by  unbalanced  revolving  parts ; 
2,  the  momentum  of  the  parts  which  have  a reciprocating  motion;  3, 
those  due  to  the  varying  pressure  of  the  steam  in  the  cylinder-heads ; and 
4,  those  caused  by  the  upward  or  downward  thrust  of  the  connecting-rods 
against  the  guide  bars. 

Question  451.  How  does  the  disturbing  effect  of  unbalanced  weights  in 
revolving  mechanism  manifest  itself? 

Answer.  In  an  ordinary  machine,  if  a revolving  shaft  or  wheel  has 
more  weight  on  one  side  of  its  centre  than  on  the  other — or  is  “out  of 
balance,”  as  it  is  called — the  machine,  unless  it  is  very  securely  fastened, 
will  shake  when  the  shaft  and  wheel  revolve  rapidly,  or  if  the  revolving 
part  is  free  to  move  laterally  it  will  “wobble.”  This  action  is  shown  if  wa 
fasten  a weight  to  one  side  of  an  ordinary  spinning  top,  or,  better  still,  if  a 
small  model  of  a pair  of  locomotive  wheels,  attached  to  an  axle,  is  sus- 
pended from  a journal-bearing  by  elastic,  india-rubber  bands,  so  that  the 
wheels  and  axle  can  turn  freely  and  also  swing  horizontally.  The  elastic 
bands  will  also  allow  the  wheels  and  axle  to  vibrate  vertically.  A twine 
should  then  be  wound  around  the  axle  and  a weight  attached  to  one  end 
of  it.  This  weight  will  cause  the  axle  and  wheels  to  revolve,  and  if  the 
wheels  and  axle  are  balanced  they  will  have  very  little  horizontal  oi 
vertical  movement ; but  if  a weight  is  attached  to  one  of  the  wheels,  at 
some  distance  from  its  centre,  and  they  are  then  made  to  revolve,  they 
will  vibrate  violently  both  vertically  and  horizontally,  owing  to  the  effect 
of  the  centrifugal  force  of  the  weight. 

Question  452.  What  is  the  cause  of  this  disturbance  in  the  movement 
of  the  wheels  ? 

Answer.  It  is  due  to  the  action  of  the  unbalanced  weight  which  exerts 
a centrifugal  force,  or  a pull  away  from  the  axle,  in  the  direction  of  a 
radius  drawn  through  the  centre  of  gravity  of  the  weight  and  the  centre 
of  the  axle. 


Internal  Disturbing  Forces  in  the  Locomotive. 


377 


QUESTION  453.  How  may  the  disturbing  action  of  the  unbalanced  weight 
be  neutralized? 

Answer.  By  attaching  an  equal  counterweight  to  the  wheel  on  the 
opposite  side  of  the  axle,  and  at  the  same  distance  from  it  as  the  first 
weight.  The  centrifugal  force  of  the  counterweight  will  then  be  exerted 
in  an  opposite  direction  to  that  of  the  first  weight,  and  the  two  will  thus 
balance  each  other,  and  there  will  then  be  no  disturbance  to  the  motion 
of  the  wheels.  If  the  weights  balance  each  other  accurately,  the  wheels 
will  have  very  little  or  no  lateral  or  vertical  movement,  showing  that  the 
effect  of  the  centrifugal  force  of  the  one  weight  neutralizes  that  of  the 
other. 

Question  454.  Is  it  essential  that  the  two  weights  should  be  at  the  same 
distance  from  the  centre  of  the  axle  ? 

Answer.  No.  All  that  is  needed  is  that  one  weight  should  balance 
the  other.  If  the  one  is  farther  from  the  axle  than  the  other,  the  first 
must  be  lighter,  or  if  it  is  nearer  it  must  be  heavier  than  the  other.  It  is 
essential  for  a perfect  balance  that  if  each  weight  is  multiplied  into  the 
distance  of  its  centre  of  gravity  from  the  centre  of  the  axle,  that  the  pro- 
ducts should  be  equal. 

Question  455.  What  effect  does  an  unbalanced  weight  on  the  crank-pin 
of  a locomotive  have  ? 

Answer.  Its  effect  is  similar  to  that  of  an  unbalanced  weight  on  any 
other  revolving  wheel  or  shaft.  Thus,  suppose  that  the  large  circles,  D , 
D 4,  D 8,  D 12  and  D 16,  figs.  307-311,  represent  the  circumference  of  a 
locomotive  driving-wheel,  A , its  axle,  and  C,  the  crank-pin  ; and  that  a 
weight,  W,  is  attached  to  the  pin,  and  turns  with  it.  When  the  wheel  is 
revolving,  and  is  in  the  position  shown  in  fig.  307,  the  weight,  W,  will 
exert  a centrifugal  force  against  the  pin  in  a direction  away  from  the  axle, 
as  indicated  by  the  dart  below  d.  The  effect  of  this  is  that  a pressure  is 
communicated  to  the  axle  which  pushes  against  the  driving-box  and 
frame,  and  the  force  thus  has  a tendency  to  move  that  side  of  the  engine 
ahead,  if  it  is  running  in  the  direction  indicated  by  the  dart,  K.  When 
the  crank-pin  is  in  the  position  shown  in  fig.  309,  the  centrifugal  force  of 
the  weight  will  push  the  crank-pin  and  wheel  backwards ; in  the  position 
shown  in  fig.  308,  it  pushes  downward,  and  in  that  in  fig.  310,  upward,  as 
indicated  in  each  case  by  the  darts,  d.  If  the  crank-pin  was  in  the  posi- 
tion represented  by  the  dotted  circle,  c,  in  fig.  307,  the  centrifugal  force 
would  be  exerted  in  a diagonal  direction,  as  indicated  by  the  dart,  c A. 
When  the  crank-pin,  C,  on  the  nearest  side  of  the  engine,  is  in  the  position 


378 


Catechism  of  the  Locomotive. 


represented  in  fig.  807,  the  crank-pin  on  the  opposite  side  is  in  the  posi- 
tion represented  by  the  dotted  circle,  C' . The  centrifugal  force  of  the 
revolving  weight  on  this  crank-pin  is  then  exerted  downward,  or  in  the 
direction  of  the  dart,  d' . In  fig.  308,  the  centrifugal  force  on  the  opposite 


Internal  Disturbing  Forces  in  the  Locomotive. 


379 


pin  pushes  backward,  in  fig.  309  upward,  and  in  fig.  310  forward.  When 
centrifugal  force  is  exerted  either  forward  or  backward  on  one  side  of  a 
locomotive,  the  tendency  is  to  produce  what  is  called  “ nosing  ” or  a 
horizontal  movement  of  its  front  and  back  ends,  around  a vertical  axis 
between  them.  When  either  of  the  crank-pins  is  above  the  axle,  as  in  fig. 
309  and  fig.  310,  the  upward  pressure  on  one  side  has  a tendency  to  lift 
that  side  of  the  engine  in  that  direction,  and  cause  a rolling  or  rocking  of 
the  engine. 

Question  456.  How  may  the  disturbing  effect  of  a weight  at  the  crank- 
pin  of  a locomotive  be  neutralized? 

Answer.  This  may  be  done  in  the  same  way  that  the  effect  of  an  un- 
balanced revolving  weight  on  any  other  wheel  or  shaft  is  counteracted,  that 
is*  by  attaching  a counterweight  opposite  to  the  crank-pin.  In  other 
words  the  revolving  parts  may  be  balanced  in  ordinary  locomotives  so  as 
to  cause  very  little  disturbance  in  the  working  of  the  engine,  by  simply 
putting  a counterweight  in  each  wheel  opposite  the  crank-pin,  as  shown 
in  fig.  339,  whose  weight,  multiplied  by  the  distance  of  its  centre  of  gravity 
from  the  centre  of  the  axle,  will  be  equal  to  the  weight  at  the  crank-pin 
multiplied  by  the  distance  of  its  centre  from  that  of  the  axle,  or  half  the 
stroke.  The  revolving  weights  of  each  wheel  consist  of  the  crank-pin 
boss,  crank-pin,  one-half  the  coupling-rod  or  rods  connected  to  the  wheel. 
For  each  of  the  main  driving-wheels,  there  must  be  added  to  these  weights 
that  of  the  back  end  of  the  main  connecting-rod. 

Question  457.  Where  are  the  counterweights  of  locomotive  driving- 
wheels  placed  a?id  how  are  they  constructed? 

Answer.  They  are  placed  between  the  spokes  of  the  wheels  as  shown 
at  A A,  fig.  339.  They  are  sometimes  made  in  two  halves,  and  bolted  to 
the  wheels  between  the  spokes,  as  shown  in  fig.  339.  In  other  cases  they 
are  cast  solid  with  the  wheels,  and  in  some  instances,  hollow  spaces  are 
made  in  the  wheels  which  are  filled  with  lead. 

Question  458.  How  can  the  reciprocating  parts  of  locomotives  be 
balanced? 

Ansiuer.  To  explain  this  it  will  be  supposed  that  c A,  fig.  312,  is  a 
crank  on  the  shaft  or  axle,  A , and  revolving  around  it,  and  that  C is  a 
weight  attached  to  the  crank-pin,  c.  If  the  crank  is  revolving  in  the 
direction  indicated  by  the  dart,  d,  then  the  weight,  if  unconstrained,  would 
move  in  a direction  at  right  angles  to  A c,  as  indicated  by  the  dart,  c f. 
Instead  of  being  free  to  move  in  that  direction  the  crank  pulls  the  weight 
toward  the  centre  of  the  wheel  and  causes  it  to  revolve  in  a circular  path 


380 


Catechism  of  the  Locomotive. 


around  the  axle.  As  the  weight  resists  this  constraint,  considerable  pull 
must  be  exerted  by  the  crank  to  draw  the  weight,  C,  from  the  path,  c /, 
which  it  would  take  if  it  was  detached  from  the  crank  when  it  reached  c, 
into  that  of  the  dotted  circle. 

This  pull  is  the  centrifugal  force  of  the  revolving  weight.  When  it 
reaches  the  position  shown  in  fig.  313,  if  it  was  free  to  move,  it  would  again 
take  the  direction,  c f,  at  right  angles  to  the  crank,  c A,  but  the  crank  con- 
tinues to  pull  it  toward  the  centre  of  the  shaft,  A,  in  the  direction,  c A,  and 


Diagrams  Showing  Action  of  Centrifugal  Force  at  the  Crank-Pin.  Scale  J4  in.=l  ft. 

compels  the  weight  to  revolve  in  a circular  path.  The  centrifugal  force 
exerted  through  the  crank  acts  in  a diagonal  direction,  c A.  By  the  prin- 
ciple of  the  parallelogram  of  forces,  if  we  let  the  radius,  c A,  of  the  crank 
represent  the  magnitude  of  the  centrifugal  force  and  construct  a parallelo-* 
gram,  e c b A,  whose  sides  are  vertical  and  horizontal  and  drawn  through 
the  centres  of  the  shaft,  A , and  crank-pin,  c,  then  the  horizontal  side,  c b , 
will  represent  the  force  required  to  move  the  weight,  C,  horizontally.  If, 


Internal  Disturbing  Forces  in  the  Locomotive. 


381 


instead  of  being  attached  to  the  crank,  the  weight,  C,  was  suspended  by  a 
cord,  C g,  so  that  it  could  swing  freely,  as  shown  in  fig.  314,  and  if  it  was 
connected  to  the  crank  by  a rod,  C c,  then  it  is  plain  that  as  much  pull 
must  be  exerted  on  this  rod  to  move  the  weight  horizontally  as  was  exerted 
by  the  crank  in  fig.  312  to  move  it  in  the  same  direction.  In  other  words, 
the  resistance  of  the  weight  to  horizontal  movement,  when  the  crank  is  at 
a dead-point,  is  just  equal  to  the  centrifugal  force  which  would  be  exerted 
through  the  crank  if  the  weight  was  attached  to  it.  When  the  crank  is  in 
the  position  represented  in  fig.  313,  it  has  been  shown  that  the  force  required 
to  move  it  horizontally  is  the  horizontal  component,  c b,  of  the  centrifugal 
force  represented  by  c A.  In  fig.  315  the  crank  is  represented  in  the  same 
position  as  in  fig.  313,  and  the  weight,  C,  is  again  connected  to  c,  by  a rod 
or  cord,  C c.  The  force  required  to  move  C horizontally  in  this  figure,  is 
the  same  as  that  required  to  move  C in  fig.  313,  excepting  as  it  is  influenced 
by  the  angle  of  the  connecting-rod,  C c,  which  may  at  present  be  disregarded. 
In  other  words,  the  force  required  to  move  C horizontally,  is  equal  to  the 
horizontal  component  of  the  centrifugal  force  of  a weight  equal  to  C,  act- 
ing at  the  crank-pin.  If  now,  we  were  to  put  a counterweight,  W,  fig. 
315,  equal  to  C,  and  opposite  to  the  crank-pin,  c,  then  the  centrifugal 
force  at  W,  would  be  equal  to  but  would  act  in  a direction,  A W,  opposite 
to  that  of  C,  in  fig.  313.  The  horizontal  component,  e'  W,  will  be  equal 
to  but  opposite  to  c b , in  figs.  313  and  315.  Therefore,  e'  W,  or  the  hori- 
zontal effect  of  the  centrifugal  force  of  the  counterweight,  W,  will  be 
equal  to  the  horizontal  force,  c b,  required  to  move  C,  and  as  they  act  in 
reverse  directions  they  will  balance  each  other. 

When  the  crank-pin,  c,  is  at  the  dead-point,  as  shown  in  fig.  314,  the 
weight,  C,  is  started  from  a state  of  rest,  and  its  motion  is  accelerated 
until  the  crank  has  made  a quarter  turn,  and  its  motion  is  then  retarded 
to  the  end  of  the  stroke,  or  until  the  crank  reaches  the  back  dead-point. 
During  the  second  half  of  the  crank’s  revolution,  the  movement  of  the 
weight,  C,  is  again  accelerated  during  the  third  quarter  and  retarded 
thereafter.  The  momentum  of  the  weight,  C,  acquired  during  the  first 
and  third  quarters  of  the  revolution,  if  not  otherwise  resisted,  will  be 
exerted  against  the  crank-pin  and  crank,  and  the  reciprocating  parts  will 
thus  be  brought  to  a state  of  rest  at  the  end  of  the  stroke.  This  produces 
an  unbalanced  pressure  of  the  crank  on  one  side  of  the  shaft,  which  has  a 
tendency  to  push  it  in  the  direction  in  which  the  pressure  is  exerted.  As 
the  shaft  is  revolving  such  a pressure  is  exerted  alternately  forward  and 
backward.  If,  however,  there  is  a counterweight,  W,  opposite  to  the 


382 


Catechism  of  the  Locomotive. 


crank,  the  horizontal  component  of  its  centrifugal  force,  as  has  been 
shown,  is  just  equal  to,  and  is  exerted  in  the  opposite  direction  to  the 
momentum  of  the  reciprocating  weight,  C,  and  thus  balances  it,  and 
relieves  the  shaft  of  the  horizontal  disturbances  due  to  the  motion  of  the 
reciprocating  parts. 

Now  the  relation  of  the  weight,  C,  in  figs.  314  and  315,  to  the  crank  is 
similar  to  that  of  the  reciprocating  parts  of  an  engine,  as  shown  in  figs. 
316  and  317,  in  which  the  cross-head,  H , is  connected  to  the  crank-pin,  c, 
by  the  rod.  He,  and  the  piston-rod,  r,  and  piston,  P,  are  attached  to  the 
cross-head,  and  they  are  all  moved  together.  When  the  crank  is  at  the 
dead-point,  as  shown  in  fig.  316,  the  force  required  to  move  the  recipro- 


d 


Fig.  318. 

Diagrams  Showing  Action  of  Counterweights.  Scale  in.=l  ft. 


eating  parts  horizontally  is  equal  to  the  centrifugal  force  of  a weight  equal 
to  these  parts,  acting  at  the  crank-pin.  Consequently,  if  we  put  a counter- 
weight, W , equal  to  the  reciprocating  parts  opposite  to  the  crank,  its 
centrifugal  force  will  be  just  equal  to  the  resistance  of  these  parts  and  will 
be  exerted  in  an  opposite  direction,  so  that  it  will  balance  or  counteract 
the  horizontal  resistance  of  the  reciprocating  parts.  When  the  crank  is  in 


Internal  Disturbing  Forces  in  the  Locomotive. 


383 


any  other  position,  as  in  fig.  317,  then  the  horizontal  component,  e'  W,  of 
the  centrifugal  force  of  TV,  will  always  be  equal  to  the  horizontal  resist- 
ance of  the  reciprocating  parts,  and  they  thus  balance  each  other. 

Question  459.  What  effect  does  the  pressure  of  the  steam  in  the  cylin- 
ders have  on  the  stability  of  a locomotive  ? 

Answer.  This  can  be  explained  if  it  be  supposed  that  we  had  an  engine 
with  a double  crank  and  two  cylinders  located  on  opposite  sides  of  the 
crank,  as  shown  in  fig.  319.  If  the  crank  should  turn  without  steam  in 


F 


G 


Fig.  319.  Diagram  Showing  Action  of  Two  Pistons.  Scale  14  in.—l  ft. 

the  cylinders,  obviously  the  reciprocating  parts  of  each  would  exactly 
balance  each  other.  If  steam  was  admitted  to  one  of  the  cylinders  so  as 
to  turn  the  crank  at  the  same  speed  that  it  was  turned  without  steam  on, 
then  it  is  plain  that  the  movement  of  the  reciprocating  parts — their 
acceleration  and  retardation,  their  inertia  and  momentum — will  be  the 
same  with  steam  on  as  they  were  without  steam.  As  they  balanced  each 
other  at  the  same  speed  without  steam  on,  they  will  be  in  equilibrium 
when  steam  is  admitted  to  one  cylinder. 

As  it  has  been  shown  that  a counterweight  opposite  the  crank  will 
balance  the  movement  of  the  reciprocating  parts,  and  as  it  is  also  obvious 
that  one  piston,  etc.,  will  balance  another,  we  may  disconnect  one  piston 
and  substitute  a counterweight  to  balance  the  other  piston  and  its  con- 
nected parts. 

It  is  true  that  if  steam  is  admitted  into  the  front  end,  S,  of  the  cylinder, 
fig.  318,  that  it  will  cause  some  disturbing  effect,  but  it  is  not  due  to  the 
motion  of  the  reciprocating  parts,  but  to  the  pressure  of  the  steam.  It 
would  press  equally  on  the  cylinder-head,  t,  and  on  the  piston,  P,  and 
these  pressures  would  balance  each  other.  The  pressure  on  the  cylinder- 
head  is,  however,  communicated  to  the  cylinder  and  frame,  that  on  the 
piston  to  the  crank-pin,  wheel,  and  thence  to  the  frame,  as  explained  in 
the  preceding  chapter,  so  that  they  both  act  on  the  pressure  in  opposite 
directions.  The  only  cause  of  disturbance  is  due  to  the  fact  that  the 
pressure  on  the  cylinder-head  is  communicated  directly  to  the  frame 


384 


Catechism  of  the  Locomotive. 


and  thence  to  the  axle,  A,  fig.  318,  and  that  on  the  piston  is  communi- 
cated to  the  crank-pin,  c.  We  will  imagine  the  spoke,  A c k,  of  the  wheel 
to  be  a lever,  and  that  the  pressure  on  the  cylinder-head  is  communicated 
through  the  frame  and  acts  against  the  axle,  as  indicated  by  the  dart,  /, 
and  that  the  pressure  on  the  piston  is  exerted  on  the  crank-pin  at  m.  If 
k,  the  point  of  contact  of  the  wheel  with  the  rail,  is  regarded  as  the  ful- 
crum of  the  lever,  then  one  force  acting  on  the  end  of  the  lever  at  A , and 
another  equal  force  acting  in  the  opposite  direction  at  c,  between  the  end, 
A,  and  the  fulcrum,  k,  will  push  the  upper  end  of  the  lever  ahead.  It  is 
this  action  which  propels  the  engine.  As  part  of  the  force  acting  on  the 
piston  is  exerted  on  the  rail,  at  k,  and  the  whole  of  that  on  the  cylinder- 
head  acts  against  the  axle,  we  have  an  excess  of  pressure  against  A,  which 
acts  on  the  engine  frame  and  tends  to  push  one  side  of  the  engine  ahead, 
and  thus  cause  nosing,  but  other  than  that  it  has  no  disturbing  effect  on 
the  action  of  the  working  parts.  If  we  will  imagine  that  the  wheels  are 
securely  bolted  fast  so  that  they  cannot  turn,  then  the  admission  of  steam 
into  the  cylinders  would  not  disturb  or  affect  their  equilibrium,  even  if 
the  engine  was  suspended  so  that  it  could  swing  freely. 

Question  460.  Will  lead  or  compression , by  admitting  steam  in  fro7it 
of  the  piston  neutralize  the  momentum  of  the  reciprocating  parts  ? 

Answer . No  ; that  they  cannot  have  this  effect  will  appear  if  we  imag- 
ine that  the  piston  should  strike  the  cylinder-head  at  the  end  of  each 
stroke.  It  would  thus  be  brought  to  a state  of  rest  by  a violent  blow.  If 
a piece  of  india-rubber  was  interposed  between  the  piston  and  cylinder- 
head  the  blow  would  be  less  violent,  but  the  energy  of  the  moving  parts 
would  still  be  communicated  to  the  cylinder-head,  as  it  would  be  if  a 
cushion  of  steam  was  interposed,  as  it  is  when  the  engine  has  lead  or 
compression,  and  the  momentum  would  then  be  overcome  in  a less  violent 
way  than  it  is  by  a cushion  of  india-rubber. 

Question  461.  Is  there  any  disturbing  influence  when  the  reciprocatmg 
parts  of  an  engine  are  balanced  by  revolving  parts  ? 

Answer.  Yes ; while  the  motion  of  reciprocating  parts  may  be  balanced 
by  a revolving  weight,  the  latter  causes  a disturbing  effect  on  the  machine, 
for  the  reason  that  the  momentum  and  inertia  of  the  reciprocating  parts 
act  in  a horizontal  direction  only,  whereas  the  revolving  weight  has  verti- 
cal as  well  as  horizontal  movement.  Thus,  if  the  crank  and  counter- 
weight are  arranged,  as  shown  in  fig.  318,  the  counterweight,  W,  in  order 
to  balance  the  reciprocating  parts,  must  be  heavier  than  the  weight  con- 
centrated at  the  crank-pin,  c,  consequently,  the  counterweight  exerts  more 


Internal  Disturbing  Forces  in  the  Locomotive. 


38  5 


centrifugal  force  than  the  crank  does,  and  when  they  are  in  the  position 
represented  the  weight,  IV,  would  exert  an  upward  pressure  greater  than 
the  downard  pressure  at  the  crank.  When  they  are  at  the  dead-points,  as 
shown  in  fig.  316,  then  if  the  counterweight,  IV,  is  equal  to  the  weight  of 
the  revolving  parts,  at  c,  and  the  reciprocating  parts,  the  centrifugal  force 
of  the  former,  and  the  momentum  and  inertia  of  the  latter  will  be  just 
equal  to  the  centrifugal  force  of  W.  When  the  crank  is  between  the  dead- 
points  and  the  two-quarters  of  its  revolution,  as  shown  in  fig.  317,  the 
centrifugal  force  of  the  counterweight  is  exerted  in  a diagonal  or  partly 
vertical  and  partly  horizontal  direction.  Between  the  two  dead-points, 
therefore,  a counterweight  which  balanced  the  weight  of  both  the  revolv- 
ing and  the  reciprocating  parts  creates  a vertical  disturbance,  which  is 
greatest  at  the  two  quarters  of  the  revolution  and  increases  from  and 
diminishes  towards  each  of  the  dead-points  where  it  disappears  entirely. 

Question  462.  How  may  the  amount  of  this  upward  and  downward 
force  be  determined  ? 

Answer.  It  is  equal  to  the  difference  between  the  centrifugal  force 
which  is  exerted  vertically  by  the  counterweight  and  the  revolving  weight 
at  the  crank-pin. 

As  an  illustration  of  the  method  of  calculating  this  upward  and  down- 
ward disturbance,  and  to  show  how  it  acts,  we  will  take  the  case  of  an  en- 
gine with  four  driving-wheels,  62  inches  in  diameter  and  24  inches  stroke, 
at  a speed  of  60  miles  per  hour.  At  that  speed  such  wheels  would  revolve 
325  times  per  minute.  Let  it  be  supposed  that  the  following  are  the 

WEIGHTS  OF  THE  REVOLVING  AND  RECIPROCATING  PARTS. 


Revolving  Parts. 

Crank-pin,  Boss,  for  each  wheel 150  lbs. 

Crank-Pin  “ “ 110  “ 

Coupling-Rod  “ “ 240  “ 

Back  End  of  Main  Connecting-Rod 190  “ 


Total  Revolving  Parts 690  lbs. 

Reciprocating  Parts. 

Front  End  of  Main  Connecting-Rod 150  lbs. 

Cross-Head 174 

Piston  and  Piston-Rod 300  “ 


Total  Reciprocating  Parts 


624  lbs. 


38G 


Catechism  of  the  Locomotive. 


It  will  be  supposed,  now,  that  the  revolving  weights  connected  to  each 
wheel  are  perfectly  balanced  in  the  respective  wheels.  As  has  been  ex- 
plained, such  balance  weights  will  not  cause  any  disturbance,  and  their 
effect  may  be  disregarded  here,  But  it  will  be  supposed,  further,  that  the 
weight  of  the  reciprocating  parts  on  each  side  is  equally  divided  between 
the  two  wheels  on  that  side.  This  will  give  312  lbs.  to  each  wheel  which 
acts  on  the  crank-pin  12  inches  from  the  centre  of  the  axle.  Therefore, 
312x12=3,744.  If,  then,  the  centre  of  gravity  of  the  counterweight 
is  20  inches  from  the  centre  of  the  axle,  the  weight  required  to  balance 
the  reciprocating  parts  will  be 

3,744 

= 187.2. 

20 

By  the  rule  given  in  answer  to  Question  167,  it  will  be  fonnd  that  the 
centrifugal  force  of  each  weight  would  be  11,205  lbs.,  and  at  70  miles  per 
hour — not  an  unusual  speed  for  locomotives — it  would  be  15,318  lbs. 
This  force,  it  will  be  observed,  is  greater  than  the  weight  which  in  many 
instances  rests  on  a single  wheel  of  a locomotive,  and  shows  why  less  than 
the  whole  of  the  reciprocating  weight  should  be  counterbalanced. 

The  manner  in  which  the  force  of  the  counterweight  is  exerted  on  the 
wheels  while  they  are  in  motion  is  illustrated  in  fig.  320,  in  which  a driv- 
ing-wheel is  represented,  at  D,  with  its  crank-pin,  C,  at  the  forward  dead- 
point.  c is  the  centre  of  gravity  of  the  counterweight,  W.  In  this  posi- 
tion its  centrifugal  force  is  exerted  in  a horizontal  direction  only,  as 
indicated  by  the  dart,  d , whose  length,  o c,  will  be  supposed  to  represent 
the  magnitude  of  the  force.  D 4,  D 8,  D 12,  and  D 16,  represent  the 
position  of  the  driving-wheel  at  the  end  of  the  first,  second,  third,  and 
fourth  quarters  of  a revolution,  and  the  circles,  4,  8,  12,  and  16,  show  the 
axle  when  the  wheel  is  in  these  positions,  and  the  dotted  circles,  1,  2,  3-15, 
represent  the  intermediate  positions  of  the  axle  during  each  sixteenth 
of  a revolution.  When  the  axle  is  in  the  position,  1,  then  the  centre  of 
gravity  of  the  counterweight  is  at  c 1,  and  its  centrifugel  force  acts  in  the 
direction  shown  by  the  dart,  d 1.  Supposing,  again,  that  the  length,  1 
c 1 , of  the  dart,  d 1,  represents  the  magnitude  of  the  centrifugal  force,  and 
that  a parallelogram,  f,  c 1,  d 1,  is  drawn  whose  sides  are  vertical  and 
horizontal  and  of  which  d 1 is  a diagonal,  then  by  the  principle  of  the 
parallelogram  of  forces,  c 1,  d,  the  vertical  side  will  be  equal  to  the  ver- 
tical component  or  effect  of  the  force,  d 1.  In  the  same  way  similar 
parallelograms  could  be  drawn  for  the  darts,  d 2,  d 3,  etc.,  but  if  the  mag- 


Internal  Disturbing  Forces  in  the  Locomotive. 


387 


nitude  of  the  centrifugal  force  is  represented  by  the  darts,  d 2,  d 3,  etc., 
all  that  is  needed  to  represent  the  vertical  effect  for  each  position  of  the 
wheel  is  to  draw  vertical  lines,  c 2 h 2,  c 3 h 3,  etc.,  from  c 2,  c 3,  etc.,  the 
extremities  of  the  darts  to  the  horizontal  line,  M N,  passing  through  the 


888 


Catechism  of  the  Locomotive. 


centres  of  the  axle,  and  these  lines  will  represent  the  vertical  effect  of  the 
centrifugal  force  of  the  counterweight  for  each  position,  c 1,  c 2,  c 3,  etc., 
of  its  centre  of  gravity.  If  we  draw  a curve,  c,  c 1,  c 2-c  16  through  each 
position  of  the  centre  of  gravity  of  the  counterweight  during  the  whole 
revolution,  its  vertical  distance  above  the  centre  line,  M N , will  represent 
the  upward  force  exerted  by  the  counterweight,  and  the  distance  of  the 
curve  below  the  line,  M N,  will  represent  the  downward  pressure  of  the 
counterweight,,  and  the  curve  will  represent  to  the  eye  the  vertical  strains 
exerted  by  the  counterweight  during  a whole  revolution  of  the  wheel.  It 
will  be  seen  from  the  diagram  that  when  the  wheel  is  in  the  position  indi- 
cated by  D,  as  already  explained,  the  centrifugal  force  is  exerted  in  a 
backward  direction — assuming  that  the  engine  is  running  from  the  right 
towards  the  left  side,  as  shown  by  the  dart,  K.  When  the  wheel  has 
turned  a quarter  of  a revolution,  as  shown  at  D 4,  then  the  centrifugal 
force,  d 4,  is  exerted  upward  ; at  D 12  it  acts  downward,  and  at  D 16  it  is 
again  backward. 

As  the  crank  on  the  other  end  of  the  axle  is  at  right  angles  to  the  one 
on  this  side,  the  centrifugal  force  of  the  counterweight  on  that  side  also 
acts  at  right  angles  to  the  one  on  this  side,  so  that  when  the  counter- 
weight, W,  exerts  a backward  horizontal  pressure,  the  opposite  one  acts 
vertically  either  up  or  down,  according  to  its  position  in  relation  to  IV. 
When  W acts  vertically,  as  at  D 4,  then  its  opposite  exerts  its  force 
horizontally. 

Question  463.  How  may  the  vertical  disturbance  of  the  counterweights 
be  lessened? 

Answer.  By  balancing  only  a part  of  the  weight  of  the  reciprocating 
parts.  When  this  is  done  there  is  more  horizontal  disturbance  in  the 
working  of  the  engine  than  there  would  be  if  the  whole  of  the  reciprocat- 
ing parts  were  balanced,  but  this  is  not  considered  so  great  an  evil  as  the 
excessive  vertical  disturbance  which  necessarily  results  when  the  counter- 
weight is  sufficient  to  balance  the  whole  of  the  horizontal  momentum  of 
the  reciprocating  parts.  Whether  a third,  a half,  two-thirds,  or  any  other 
proportion  of  these  parts  should  be  balanced  is  a question  which  must  be 
largely  decided  by  experience  and  practical  considerations.  If  a half  is 
balanced  it  divides  the  vertical  and  horizontal  disturbance  equally,  but 
there  is  still  much  difference  of  opinion  with  reference  to  which  is  the 
greater  evil. 

Question  464.  To  calculate  the  weight  of  a counterbalance  what  else 
must  be  known  ? 


Internal  Disturbing  Forces  in  the  Locomotive. 


389 


Answer.  We  must  know  the  position  of  its  centre  of  gravity. 
Question  465.  How  can  the  centre  of  gravity  of  a counterweight  in  one 
segment  be  found? 

Answer.  By  CUTTING  A WOODEN  TEMPLET  OF  UNIFORM  THICKNESS 
TO  THE  FORM  OF  THE  SURFACE,  AND  FREELY  SUSPENDING  IT  BY  ONE  OF 
THE  CORNERS,  a,  AS  IN  FIG.  321  ; A PLUMMET-LINE,  a P,  DROPPED  FROM 


Fig.  321.  Method  of  Finding  Centre  of  Gravity  of  Counterweight. 

THE  SAME  POINT  OF  SUSPENSION  IN  FRONT  OF  THE  TEMPLET,  WILL  IN- 
TERSECT THE  CENTRE  LINE,  b C,  AT  THE  CENTRE  OF  GRAVITY,  C. 

Question  466.  How  can  the  centre  of  gravity  of  a counterweight  in 
three  segments  be  found? 

Answer.  Find  the  centre  of  gravity,  C,  fig.  322,  of  one  of  the 
COUNTERWEIGHTS,  AS  ABOVE;  THROUGH  C STRIKE  AN  ARC  FROM  THE 
CENTRE,  a,  OF  THE  WHEEL,  CROSSING  THE  CENTRE  LINES  OF  THE  OTHER 
SEGMENTS  AT  THEIR  CENTRES,  C'  C" ; DRAW  C'  C"  MEETING  A B AT  D, 
AND  SET  OFF  D E,  ONE-THIRD  OF  THE  INTERVAL  D C.  THEN  E IS  THE 
COMMON  CENTRE  OF  GRAVITY  OF  THE  THREE  SEGMENTS. 

Question  467.  How  can  the  centre  of  gravity  of  a counterweight  in  two 
segments  be  found  ? 

Answer.  This  is  required  when  the  crank  is  opposite  to  a spoke,  as  in 


390 


Catechism  of  the  Locomotive. 


fig.  323.  Find  the  centre  of  gravity,  C,  of  one  segment  as  be- 
fore, AND  BY  AN  ARC  FIND  THE  OTHER  CENTRE,  C' ; DRAW  C C\  CUT- 
TING A B at  D,  which  is  the  common  centre  of  gravity. 


Question  468.  How  can  the  centre  of  gravity  of  a counterweight  in 
four  segments  be  found  ? 


Fig.  323.  Method  of  Finding  Centre  of  Gravity  of  Two  Counterweights. 

Answer.  FIND,  AS  BEFORE,  THE  CENTRES,  C C'  C"  C"\  FIG.  324,  OF 


Internal  Disturbing  Forces  in  the  Locomotive. 


391 


THE  SEGMENTS;  DRAW  C"  C AND  C"'  C,  CUTTING  THE  LINE  A B ; 
BISECT  THE  INTERVAL  SO  ENCLOSED  AT  E FOR  THE  COMMON  CENTRE  OF 
GRAVITY.* 

Question  469.  How  may  the  counterweights  be  calculated ? 

Answer.  Find  the  separate  revolving  weights,  in  pounds,  of 

CRANK-PIN,  CRANK-PIN  BOSS,  COUPLING-RODS  AND  BACK  END  OF  CON- 


Fig.  324.  Method  of  Finding  Centre  of  Gravity  of  Four  Counterweights. 

NECTING-ROD,  FOR  EACH  WHEEL  ; ALSO  THE  RECIPROCATING  WEIGHT  OF 
THE  PISTON  AND  APPENDAGES,  AND  THE  FRONT  END  OF  CONNECTING- 
ROD  ; TAKE  FIVE-EIGHTHSf  OF  THE  RECIPROCATING  WEIGHT  AND  DIVIDE 
IT  EQUALLY  BETWEEN  THE  COUPLED  WHEELS,  AND  ADD  THE  PART,  SO 
ALLOTTED,  TO  THE  REVOLVING  WEIGHT  ON  EACH  WHEEL  ; THE  SUMS  SO 
OBTAINED  ARE  THE  WEIGHTS  TO  BE  BALANCED  AT  THE  SEVERAL 
WHEELS;  MULTIPLY  THESE  WEIGHTS  BY  THE  LENGTH  OF  CRANK  IN 
INCHES,  AND  DIVIDE  BY  THE  DISTANCE  IN  INCHES  OF  THE  CENTRE  OF 
GRAVITY  OF  THE  SPACE  TO  BE  OCCUPIED  BY  THE  COUNTERWEIGHT.  THE 
RESULT  WILL  BE  THE  COUNTERWEIGHT  IN  POUNDS,  TO  BE  PLACED 
DIAMETRICALLY  OPPOSITE  TO  THE  CRANK-PIN. 

Question  470.  What  effect  does  the  action  of  the  connecting-rods  have 
07i  the  stability  of  a locomotive  ? 

Answer.  When  a locomotive  is  running  forward,  the  pressure,  in  the 
guide-bars,  due  to  the  angle  of  the  connecting-rod — excepting  at  the  dead- 
points — is  upward  during  both  the  forward  and  backward  strokes  of  the 
piston.  As  this  pressure  is  nearly  at  its  maximum  on  one  side  when  it 
ceases  entirely  on  the  other,  its  tendency  is  to  cause  the  locomotive  to  roll. 

* These  rules  and  illustrations  for  ascertaining  the  centre  of  gravity  of  a counterweight  are 
taken  from  D.  E.  Clark’s  Railway  Machinery. 

t As  remarked  before,  from  one-half  to  three-quarters  of  this  weight  may  be  taken  in  making 
the  calculations. 


CHAPTER  XX. 


THE  RUNNING  GEAR. 

QUESTION  471.  What  is  meant  by  the  running  gear  of  a locomotive  ? 

Answer . It  means  those  parts,  such  as  the  wheels,  axles,  and  frames, 
which  carry  the  other  parts  of  the  engine.  As  the  Germans  express  it,  it 
is  the  “ wagon  ” of  the  locomotive. 

Question  472.  How  may  the  wheels  be  classified? 

Answer.  As  driving  and  carrying  or  truck  wheels? 

Question  473.  What  service  must  the  driving-wheels  perform  ? 

Answer.  The  driving-wheels,  as  indicated  by  their  name,  “ drive  ” or 
move  the  locomotive  on  the  track,  as  was  explained  in  answer  to  Ques- 
tions 176,  177  and  178.  As  their  adhesion  depends  upon  the  pressure 
with  which  they  bear  upon  the  rails,  they  must  carry  either  a part  or  the 
whole  of  the  weight  of  the  engine. 

Question  474.  What  is  a “truck”  of  a locomotive  ? 

Answer.  A truck  consists  of  one  or  more  pairs  of  wheels  held  in  a 
separate  frame,  which  is  attached  to  the  locomotive  by  a flexible  connec- 
tion— usually  a king-bolt  or  centre-pin — somewhat  as  the  front  axle  of  an 
ordinary  wagon  or  carriage  is  fastened  to  the  body.  The  truck  is  not 
connected  rigidly  to  the  rest  of  the  locomotive,  but  it  can  turn  or  oscillate 
about  the  king-bolt,  so  that  the  axles  can  assume  positions  which  approxi- 
mate to  that  of  radii  of  the  curves  of  the  track.  In  Plates  III,  IV  and  V, 
6 C are  the  truck  wheels,  75  the  truck  frame,  and  98,  Plate  IV,  the  centre- 
pin,  around  which  the  truck  frame  turns. 

Question  475.  What  service  does  the  truck  perform  ? 

Answer.  It  usually  carries  the  weight  of  the  front  end  of  the  locomo- 
tive, and  also  guides  it  into  and  around  curves  and  switches*  Sometimes 
a truck  is  placed  under  the  back  end  of  a locomotive  to  carry  part  of  its 
weight. 

Question  476.  How  does  a truck  guide  a locomotive  on  a curved  track? 

Answer.  It  does  it  very  much  in  the  same  way  as  the  front  wheels  of 

* A switch  is  a movable  pair  of  rails  by  which  a locomotive  is  enabled  to  run  from  one  track 
to  another. 


The  Running  Gear. 


393 


an  ordinary  wagon  enable  it  to  turn  around  corners — that  is,  the  truck 
wheels  are  attached  to  a separate  frame,  which  is  connected  to  the  loco- 
motive by  a centre-pin,  so  that  they  can  turn  just  as  the  front  axle  of  an 
ordinary  wagon  can  which  is  connected  to  the  body  by  a king-bolt. 

Question  477.  Why  are  two  pairs  of  wheels  usually  used  on  a locomo- 
tive truck  instead  of  one , as  071  an  ordinary  wagon  ? 

Answer.  Because  it  is  necessary  to  have  one  pair  of  wheels  guide  the 
other.  In  a wagon  the  front  axle  is  guided  by  the  pole  or  shafts.  Nearly 
every  one  knows  the  difficulty  of  moving  such  a vehicle  when  the  pole  or 
shafts  are  removed,  especially  if  it  be  pushed  from  behind.  The  movement 
of  the  front  axle  is  then  uncontrolled,  and  it  is  impossible  to  direct  its 
movement.  The  same  thing  would  occur  with  a locomotive  if  a single 


Action  of  Single  Pair  of  Wheels  on  Track.  Scale  J4  in.=l  ft. 

pair  of  wheels  were  used  and  attached  in  the  same  way  as  the  front  axle 
of  a wagon  is.  Thus,  if  a single  pair  of  wheels  was  connected  to  a loco- 
motive by  a centre-pin,  s,  fig.  325,  so  that  the  axle  would  be  free  to  move 
around  this  pin,  then  if  one  of  the  wheels  should  strike  an  obstruction, 
Say  a stone,  a,  fig.  327,  there  would  be  nothing  to  prevent  the  axle  from 
being  thrown  into  the  position  shown  in  fig.  326,  and  the  wheels  would  be 
liable  to  leave  the  track.  When  two  pairs  of  wheels  are  used,  as  shown 
in  fig.  328,  and  both  axles  attached  to  the  same  frame,  which  is  connected 


394 


Catechism  of  the  Locomotive. 


The  Running  Gear. 


395 


to  the  engine  by  a centre-pin,  s,  between  the  two  axles,  then  the  wheels  in 
moving  round  the  centre-pin  must  move  around  it  in  arcs  of  circles,  m n , 
m n , described  from  the  centre,  s.  These  arcs,  it  will  be  observed,  cross 
the  rails.  Now,  if  the  wheels  should  move  in  the  direction  indicated  by 
the  arcs,  the  flange  of  one  of  them  would  come  in  contact  with  the  rail 
and  prevent  it  from  moving  any  farther.  It  is,  therefore,  evident  that 
wheels  arranged  in  that  way  can  only  move  about  the  centre-pin  as  far  as 
the  curvature  of  the  track  will  permit.  Trucks  are  sometimes  used  with 
only  one  pair  of  wheels,  but  the  centre-pin  is  then  placed  some  distance 
behind  the  centre  of  the  axle,  or  in  the  same  relation  to  it  that  the  centre, 
s,  is  to  the  axle,  a a' , in  fig.  328.  It  is  evident,  then,  that  if  the  frame  for 
such  a truck  should  turn  around  the  centre-pin,  the  wheels  must  move 
across  the  track  in  the  same  way  as  represented  by  the  arcs,  in  n , in  fig. 
328.  The  construction  and  operation  of  trucks  with  a single  pair  of 
wheels  will  be  more  fully  explained  hereafter. 

Question  478.  Why  will  a locomotive  run  around  curves  easier  if  the 
front  axles  are  attached  to  a truck  frame  which  is  connected  to  the  locomo- 
tive by  a flexible  connection. 

Answer.  Because  the  truck  axles  can  then  assume  positions  which  con- 
form very  nearly  to  the  radii  of  the  curves  of  the  track,  and  it  is  well 
known  that  if  two  or  more  axles,  each  with  a pair  of  wheels  on  it,  are 
attached  to  a frame  with  their  centre  lines  parallel  with  each  other,  as 
shown  in  fig.  329,  they  will  roll  in  a straight  line,  but  if  the  centre  lines  of 
the  axles  are  inclined  to  each  other,  as  shown  in  fig.  330,  the  tendency 
will  be  to  roll  in  a curve,  the  radius  of  which  will  depend  upon  the  degree 
of  inclination  of  the  axles  to  each  other.  In  order  to  make  the  wheels,  in 
fig.  329,  roll  on  the  curves,  c p d,  and  a m b,  it  will  be  necessary  to  slide 
them  laterally  a distance  equal  to  that  between  the  curves  and  the  straight 
lines,  q p r,  and  o m n,  and  as  the  length  of  the  outside  curve  is  greater 
than  the  inside  one,  if  the  wheels  are  fastened  to  the  axles  so  they  cannot 
turn  on  them  and  roll  on  the  curves,  either  the  wheels  on  the  inside  or 
those  on  the  outside  must  slip  a distance  equal  to  the  difference  in  the 
length  of  the  two  rails.  Considerable  force  will  therefore  be  required  to 
overcome  the  resistance  due  to  the  combined  lateral  and  circumferential 
sliding  of  the  wheels,  so  that  more  power  will  be  needed  to  make  them 
roll  in  a curve  than  is  necessary  to  make  them  roll  in  a straight  line.  If, 
however,  the  axles  are  inclined  to  each  other,  then  the  wheels  will  natu- 
rally  roll  on  a curved  path,  and  it  will  not  be  necessary  to  slide  them  side- 
ways to  make  them  conform  to  such  a path.  But  if  the  wheels  are  all. 


396 


Catechism  of  the  Locomotive. 


attached  to  the  axles,  so  that  those  on  the  same  axle  cannot  turn  inde- 
pendently of  each  other,  and  are  all  of  the  same  diameter,  then  either  the 
inside  or  the  outside  ones  must  slip,  because  the  path  in  which  the  out- 
side ones  roll  is  longer  than  the  inside  curve,  so  that  even  if  the  axles  are 
inclined  to  each  other  more  power  will  be  needed  to  roll  the  truck  in  a 
curved  path  than  to  roll  the  wheels,  shown  in  fig.  329,  in  a straight  line. 


Action  of  Coned  Wheels.  Scale  in.  = 1 ft. 

A cone  or  a portion  of  a cone,  like  that  shown  in  fig.  331,  will  roll  in  a 
curved  path.  It  will  do  the  same  if  the  middle  is  cut  away,  as  indicated 
by  the  dotted  lines  in  fig.  331,  and  as  shown  by  full  lines  in  fig.  332.  If, 
now,  the  wheels  are  made  so  that  their  peripheries  * form  portions  of  a cone 
and  the  axles  are  inclined  to  each  other,  as  shown  in  fig.  333,  then  there 
will  be  no  slipping  on  the  track,  because  the  outside  wheel,  being  larger 
in  diameter  than  the  inside  one,  advances  further  in  the  revolution  than 
the  latter  does,  and  thus  rolls  on  the  longest  path  in  the  same  time  that 
the  inside  or  smaller  wheel  does  on  the  shorter  one.  When  this  is  the 
case,  such  wheels  will  roll  in  a curve  as  easily  as  those  in  fig.  329  will  in  a 
straight  line.  The  degree  of  inclination  of  the  axles  and  of  the  sides  of 
the  cone  must,  however,  vary  with  the  radius  of  the  curve.  But  if  the 
axles  are  parallel  to  each  other,  and  the  wheels  conical,  as  represented  in 

* The  periphery  is  the  outside  surface  on  which  the  wheel  rolls.  This  part  of  a wheel  is 
usually  called  the  “ tread." 


The  Running  Gear. 


397 


fig.  334,  they  will  not  roll  either  in  a straight  line  or  in  a curve  without 
great  difficulty,  because  if  they  roll  in  a straight  line,  the  wheels  on  one 
side  being  larger  in  diameter  than  those  on  the  other,  either  the  larger  or 


tne  smaller  ones  must  slip  on  the  path  in  which  they  roll.  If  they  roll  on  a 
curve,  then  each  pair  of  wheels  has  a tendency  to  roll  in  a curve  indepen- 
dent of  the  other,  and  therefore  the  wheels  must  slip  laterally,  if  both  pairs 
roll  on  the  same  track.  Thus,  suppose  two  pairs  of  wheels,  a a'  and  b b' , 
fig.  334,  to  be  made  conical  and  attached  to  a frame  so  that  their  axles  are 
parallel  to  each  other ; each  pair  of  such  wheels  will  then  have  a tendency 
to  roll  in  circular  paths,  a'  z,  a h,  and  b'  k,  b j,  the  centres  of  which  are  at  m 
and  n,  or  at  the  apices  of  the  cones  of  which  their  peripheries  form  a part. 
If  they  are  made  to  roll  in  circular  paths,  ef,cd , described  from  a centre, 
g,  then  each  pair  of  wheels  must  slip  laterally  over  the  space  between  the 
paths,  a ' i and  a h , in  which  they  would  naturally  roll  and  that  in  which 
they  are  made  to  roll.  Thus,  the  wheel,  a , would  slide  laterally  the  dis- 
tance between  the  curve,  a h and  a f,  and  a'  that  between  a'  i and  a' d;  b 
would  slide  from  b j to  b f,  and  b'  from  b'  k to  b' d.  It  will  thus  be  seen 
that  in  order  that  two  pairs  of  wheels  may  roll  with  equal  ease  in  a 
straight  line  and  in  curves,  the  wheels  in  the  one  case  must  be  of  equal 
diameters  and  the  axles  parallel,  and  in  the  other  case  the  wheels  must  be 
of,  unequal  diameters  and  their  axles  be  radial * to  the  curve.  This  is 
equally  true  of  any  number  of  pairs  of  wheels.  If  we  have  three,  four,  or 
any  number  of  axles,  with  wheels  all  attached  to  the  same  frame,  if  their 

*That  is,  that  their  centre  lines  incline  toward  each  other,  and  if  extended  far  enough  would 
meet  at  tne  centre  of  the  curve. 


V 

•Fig.  334.  Action  erf  Two  Pairs  of  Coned  Wheels  on  Curve.  Scale  J4  in.=l  ft. 


The  Running  Gear. 


399 


axles  are  parallel,  and  the  wheels  of  the  same  diameter,  they  will  roll  in  a 
straight  line ; but  if  their  wheels  are  conical  and  their  axles  radial,  they 
will  roll  in  a curve. 

For  the  preceding  reasons  it  is  sufficiently  obvious  that  if  a locomo- 
tive is  to  run  on  both  straight  and  curved  tracks,  on  the  former  the 
wheels  should  be  of  the  same  diameter  and  the  axles  parallel,  and  on  the 
latter  the  wheels  should  be  conical  and  the  axles  radial. 

Question  479.  How  are  wheels  made  so  that  on  curves  they  will  act  as 
though  they  were  of  the  conical  form  described  and  on  a straight  truck  all 
be  of  the  same  diameters  ? 

Answer.  The  periphery  or  tread  of  each  wheel  is  made  conical,  but  of 
the  same  size  as  the  other,  and  with  the  small  diameters  of  the  cones  out- 
side, as  shown  in  fig.  335.  The  flanges  are  then  put  closer  together  than 


Action  of  Coned  Wheels,  Scale  Y\  in.=l  ft. 


the  rails,  so  that  there  will  be  some  space  or  end  play,  as  it  is  called,  be- 
tween the  flanges  and  the  rails,  as  shown  at  s s'.  On  a straight  track,  if 
the  position  of  the  wheels  on  the  rails  is  such  that  their  two  flanges  are 
equally  distant  from  the  rails,  as  shown  in  fig.  335,  then  obviously  at  the 
points  of  contact  with  the  rails  or  on  the  lines,  a and  b,  the  wheels  are  of 
the  same  diameter.  But  in  running  on  a curved  track  the  wheels,  as  has 
been  shown,  will  roll  toward  the  outer  rail  of  the  curve.  The  flange,  c — 
supposing  it  to  be  on  the  outside  of  the  curve — will  therefore  roll  towards 
the  rail,  and  consequently  the  outside  wheel  will  rest  on  the  rail  at  a point 
nearer  the  flange,  as  shown  in  fig.  336,  where  the  diameter,  a,  is  larger. 


400 


Catechism  of  the  Locomotive. 


and  the  inside  wheel,  b,  will  rest  on  the  rail  at  a point  farther  from  the 
flange  where  the  diameter,  b,  is  smaller  than  at  a and  b,  in  fig.  335 ; and 
consequently  the  action  of  the  wheels  is  the  same  as  though  their  periph- 
eries were  made  of  the  form  shown  in  fig.  332. 

Question  480.  Does  the  conical  form  of  wheels  have  much  influence  on 
their  action  on  curves  ? 

Anszuer.  No  ; for  the  reason  that  while  the  conical  form  of  the  wheels 
will  cause  a single  pair  on  one  axle  to  roll  in  a curved  path,  if  the  axles  of 
two  pairs  of  such  wheels  are  held  parallel  to  each  other,  as  they  are  in  a 
locomotive  or  truck  frame,  the  conical  form  has  very  little  influence  to 
act  in  that  way.  It  has  also  been  proved  by  experiment  that  when  the 
axles  are  parallel  to  each  other,  the  influence  of  the  conical  form  of  the 
wheels  diminishes  as  the  distance  between  the  axles  increases,*  so  that  at 
the  usual  distance  apart  of  the  driving-axles  of  locomotives  and  of  truck 
axles  of  locomotives  and  cars,  the  effect  of  the  conical  form  of  the  wheels 
is  almost,  if  not  quite,  inappreciable.  Besides  this,  the  conicity  of  the 
treads  of  wheels  is  rapidly  worn  away,  so  that  it  seems  quite  certain  that 
the  advantages  resulting  from  coning-wheels  are  more  imaginary  than 
real. 

QUESTION  481.  Is  the  resistance  to  rolling  diminished  by  placing  the 
truck  axles  nearer  together  ? 

Answer.  It  is  within  certain  limits.  The  nearer  each  other  they  are 
placed,  the  closer  will  the  centre-pin  of  the  truck  be  to  the  centre  of  the 
axles.  The  closer  it  is  to  the  centre  of  the  axles,  the  greater  is  the  ten- 
dency of  the  wheels  to  become  “ slewed,”  or  to  assume  a diagonal  posi- 
tion to  the  rails,  as  represented  in  fig.  326,  which  increases  the  resistance 
and  also  the  danger  of  running  off  the  track.  The  increase  of  resistance 
from  this  cause,  after  the  axles  reach  a certain  distance  from  each  other, 
is  greater  than  the  decrease  from  a closer  approximation  to  the  position 
of  radii.  In  ordinary  locomotives  it  is  necessary  to  place  the  truck  wheels 
from  5 ft.  6 in.  to  6 ft.  6 in.  apart,  in  order  to  get  the  cylinders  between 
them  in  a horizontal  position.  This  distance  apart  works  very  well  in 
ordinary  practice. 

Question  482.  What  is  meant  by  flange  friction? 

Answer.  It  is  the  friction  of  the  flanges  of  the  wheels  against  the  head 
of  the  rails.  Thus  if  two  pairs  of  wheels,  a a ' , b b' , fig.  328,  be  placed  on 

* This  was  shown  in  a paper  read  by  the  author  at  the  annual  convention  of  the  Master  Car 
Builders’  Association,  held  in  1884,  and  which  was  published  in  the  report  of  the  proceedings  of 
the  convention  of  that  year. 


The  Running  Gear. 


401 


a curve  and  rolled  in  the  direction  indicated  by  the  dart,  s,  the  wheel,  a, 
will  roll  toward  the  outside  of  the  curve  until  the  flange  conies  in  contact 
with  the  rail.  As  already  explained,  if  two  axles  are  parallel  to  each  other, 
no  matter  whether  the  wheels  are  conical  or  cylindrical,  they  must  slip 
laterally  in  order  to  roll  in  the  curved  path  into  which  the  rail  is  bent. 
As  the  wheel  offers  considerable  resistance  to  sliding  laterally,  there  is  a 
corresponding  pressure  of  the  flange  against  the  rail,  and  consequently 
the  revolutions  of  the  wheel  produce  an  abrasive  action  between  the  two. 
This  action  is  obviously  increased  with  the  distance  between  the  axles, 
because,  as  has  been  shown,  the  lateral  slip  of  the  wheels  is  then  greater 
than  when  they  are  nearer  together.  It  is  also  obvious  that  if  the  wheels 
are  parallel  with,  the  rails,  there  will  be  no  abrasive  action  of  the  flanges, 
but  that  the  greater  the  angle  at  which  the  wheels  stand  to  the  rails  the 
harder  will  the  flanges  rub  against  the  rails,  and  the  greater  will  be  the 
flange  friction.  With  the  aid  of  geometry,  it  can  very  easily  be  proved 
that  the  farther  apart  two  parallel  axles  are,  the  greater  will  be  the  angle 
of  the  wheels  to  the  rails  on  a curved  track,  and,  therefore,  the  greater 
will  be  their  flange  friction.  It  must,  however,  be  remembered  that  if  the 
wheels  are  so  close  together  that  they  are  liable  to  become  “ slewed,”  or 
assume  a diagonal  position  across  the  rails,  as  shown  in  fig.  326,  the  angle 
of  the  wheels  to  the  rails  would  thus  be  very  much  increased.  It  has, 
therefore,  come  to  be  a very  generally  recognized  rule  that  the  centres  of 
axles  should  never  be  placed  nearer  together  than  the  distance  between 
the  rails. 

QUESTION  483.  Is  the  flange  friction  of  all  the  wheels  of  a truck  the 
same  on  any  given  curve? 

Answer.  No  ; of  the  front  wheels,  a and  a',  fig.  328,  obviously  only  the 
flange  of  the  one,  a , on  the  outside  of  the  curve  comes  in  contact  with 
the  rail.  As  the  centrifugal  force  of  the  engine  presses  the  back  pair  of 
wheels  toward  the  outside  of  the  curve,  the  flange  of  the  outside  wheel,  b, 
alone  comes  in  contact  with  the  rail.  But  as  this  wheel  is  constantly 
rolling  away  from  the  rail,  as  shown  by  the  dotted  line,  h e,  obviously  the 
friction  of  its  flange  is  less  than  that  of  the  front  outside  wheel,  a,  which 
always  rolls  toward  the  rail.  The  flange  of  the  back  inside  wheel,  b' , is 
carried  outward  by  the  centrifugal  force  and  also  by  the  tendency  of  the 
outside  wheel,  b , to  roll  on  its  largest  diameter  on  a curve,  so  that  the 
flange  of  b'  will  not  ordinarily  touch  the  rail. 

Question  484.  How  does  a truck  allow  the  axles  of  a tocomotive  to> 
adjust  themselves  to  the  curvature  of  the  track? 


St 


404 


Catechism  of  the  Locomotive. 


Answer.  The  truck  is  attached  to  the  locomotive  by  a flexible  connec- 
tion or  centre-pin,  s,  as  shown  in  fig.  337  (which  represents  a plan  of  the 
wheels  of  an  ordinary  locomotive),  from  which  it  can  be  seen  that  the 
truck  axles,  e /and^*  h,  instead  of  remaining  parallel  to  the  driving-axles, 
a b and  c d , will,  by  turning  around  the  centre-pin,  s,  adjust  themselves  to 
the  curve  so  as  to  approximate  as  closely  to  radii  as  is  possible  for  two 
axles  which  are  that  distance  apart  and  are  held  parallel  to  each  other. 
Of  course,  the  farther  apart  they  are  the  greater  will  be  their  divergence 
from  the  position  of  radii,  and  whether  the  tread  of  the  wheels  be  cylindri- 
cal or  conical,  the  farther  apart  their  axles  are  the  greater  will  be  the 
divergence  of  the  paths  in  which  they  would  naturally  roll  from  that  of 
the  curve  of  the  track  on  which  they  must  roll.  Thus,  if  the  axles  were 
twice  as  far  apart  as  they  are  represented  in  fig.  334,  and  were  in  the  posi- 
tion shown  in  the  dotted  lines,  l /'  and  o o',  the  wheels,  if  they  were  conical, 
would  then  naturally  roll  in  curves  drawn  from  the  centres,  / and  q.  If 
the  wheels  are  cylindrical,  they  would  roll  in  straight  lines.  In  either  case 
the  divergence  of  their  paths,  l s and  /'  r , from  the  curve  of  the  track  is 
greater  than  a h and  a'  i,  the  paths  in  which  they  would  roll  if  their  axles 
were  nearer  together.  This  divergence  increases  with  the  distance  between 
the  axles,  and  therefore  the  lateral  slip  of  the  wheels  must  be  in  the  same 
proportion. 

Question  485.  How  is  a truck  with  a single  pair  of  wheels  arranged? 

Answer.  The  axle  is  attached  to  an  A-shaped  frame,. shown  at  a b s in 
fig.  338,  which  is  the  plan  of  an  engine  with  three  pairs  of  driving-wheels 
and  such  a truck.  The  truck  frame  is  connected  to  the  engine  with  a pin, 
s,  about  which  it  can  turn,  and  in  this  way  the  axle  can  adjust  itself  to  the 
positions  of  the  radii  of  the  curve. 

QUESTION  486.  Can  the  axles  of  driving-wheels  assume  positions  radial 
to  the  track? 

Answer.  In  ordinary  engines  they  cannot.  Various  plans  have  been 
devised  for  the  purpose  of  enabling  them  to  do  so,  but  they  have  not  met 
with  much  favor.  It  is,  however,  of  less  importance  that  the  driving-axles 
when  they  are  behind  the  centre  of  the  locomotive,  should  assume  posi- 
tions radial  to  a curved  track  than  that  the  front  wheels  should.  This  is 
illustrated  by  a common  road  wagon,  as  all  know  the  ease  with  which  a 
vehicle  can  turn  a corner  if  we  run  it  with  the  front  axle  ahead,  and  the 
difficulty  of  doing  so  when  the  back  axle  is  in  front.  In  the  case  of  a 
locomotive,  the  reason  for  it  is  very  much  the  same  as  that  which  makes 
the  flange  friction  of  the  back  wheels  of  a truck  less  than  that  of  the  front 


The  Running  Gear. 


405 


ones.  From  fig.  337  it  will  be  seen  that  the  outside  driving-wheels,  a and 
c,  when  the  engine  is  running  with  the  truck  in  front,  are  rolling  from  the 
rail  and  not  against  it.  As  stated  before,  the  centrifugal  force  of  the 
engine  when  in  motion  has  a tendency  to  throw  the  wheels  toward  the 
outside  of  the  curve.  It  will  also  be  noticed,  from  fig.  337,  that  the  front 
driving-axle  is  near  the  centre  of  that  portion  of  the  curve  which  lies 
between  the  centre,  s,  of  the  truck  and  the  centre,  k,  of  the  back  axle.  If 
it  were  in  the  middle,  between  them,  it  would  be  exactly  radial  to  the 
curve  ; being  near  the  middle,  it  approximates  closely  to  that  position, 
and  therefore  the  flange  friction  of  its  wheels  is  very  slight.  It  will  be 
seen,  too,  that  if  the  flange  of  the  back  or  trailing-wheel,  b , on  the  inside 
of  the  curve  was  not  kept  away  from  the  rail,  it  would  roll  toward  and 
impinge  against  it,  and  that  the  flange  of  the  front  driving-wheel,  d , will 
come  in  contact  with  the  inside  rail  before  that  on  the  back  wheel  can 
touch  it.  For  this  reason,  and  also  on  account  of  the  effect  of  the  centri- 
fugal force  exerted  on  the  engine  and  the  tendency  of  the  wheels  to  roll  on 
their  largest  diameters,  the  flange  of  the  inside  back  wheel  is  kept  out  of 
contact  with  the  rail,  and  as  the  back  wheel,  a , on  the  outside  of  the  curve 
rolls  away  from  the  rail,  there  is  very  little  friction  of  the  flanges  of  the 
back  driving-wheels. 

It  will  also  be  observed  from  fig.  337,  that  if  the  radius  of  the  curve  is 
very  short,  the  bend  of  the  rails  between  the  back  pair  of  driving-wheels, 
a b,  and  the  centre  of  the  truck  is  so  great  that  the  inside  rail  will  press 
hard  against  the  flange  of  the  front  or  main  driving-wheel,  d , next  that 
rail.  This,  of  course,  produces  a great  deal  of  friction,  and  if  the  curve  is 
excessively  short  the  flange  will  mount  on  top  of  the  rail,  and  the  tread  of 
the  opposite  wheel  will  fall  off  from  its  rail.  For  this  reason  the  centre- 
pin  of  the  truck  is  sometimes  arranged  so  that  it  can  move  laterally — that 
is  crosswise  of  the  track.  The  front  wheels  of  locomotives  are  also  some- 
times made  with  wide  “flat  ” tires — that  is,  tires  without  flanges,  so  that 
there  will  be  no  friction  against  the  one  rail  and  no  danger  of  falling  off 
the  other. 

Another  action  also  takes  place  which  facilitates  the  motion  of  the 
driving-wheels  of  ordinary  engines  around  curves.  Every  one  knows  how 
easily  the  direction  in  which  the  front  wheels  of  a common  wagon  move 
can  be  controlled  by  taking  hold  of  the  end  of  the  tongue  or  pole.  With 
the  leverage  which  it  gives,  the  wheels  and  axle  can  easily  be  directed 
wherever  it  is  desired.  A similar  action  takes  place  in  an  ordinary  loco- 
motive. The  front  driving-axles  are  guided  by  the  truck,  which  is  attached 


406 


Catechism  of  the  Locomotive. 


to  the  locomotive  frames  10  or  12  feet  in  front  of  the  driving-axle,  and 
thus  the  truck  exerts  a leverage  to  guide  the  movement  of  the  driving- 
axles,  just  as  a common  wagon  can  be  guided  by  the  pole. 

If  the  locomotive  is  run  backward,  then  none  of  these  advantages  exist, 
and  the  flange  friction  of  the  back  driving-wheels  is  excessive.  From  this 
cause  engines,  such  as  construction  locomotives,  which  run  backward  as 
much  as  forward,  wear  out  the  flanges  of  the  back  wheels  very  rapidly  on 
crooked  roads. 

Question  487.  What  is  meant  by  the  “ spread"  of  the  wheels  or  axles? 

Answer.  It  is  the  distance  between  the  centres  of  the  axles. 

Question  488.  What  is  the  “ wheel-base  ” of  a locomotive  ? 

Answer.  It  is  the  distance  between  the  centres  of  the  front  and  back 
or  trailing-wheels.  On  ordinary  engines,  such  as  that  illustrated  in  Plate 


Fig.  339.  Driving-Wheels. 


Ill,  it  is  usually  measured  from  the  centre  of  the  front  truck  to  the  centre 
of  the  back  driving-wheels. 

Question  489.  How  are  the  driving-wheels  of  locomotives  constructed? 

Answer.  In  this  country  they  are  made  of  cast  iron  with  wrought-iron 
or  steel  tires  around  the  outside.  Fig.  839  represents  a perspective  view 
of  a pair  of  locomotive  wheels  and  axle.  The  central  portion  of  the  wheel 


The  Running  Gear. 


407 


— that  is,  the  hub,  spokes,  and  rim,  are  cast  in  one  piece.  Usually  the 
hub  and  the  rim,  and  sometimes  the  spokes,  are  cast  hollow.  The  central 
portion  of  the  wheel — that  is,  the  part  which  is  made  of  cast  iron,  is  called 
the  wheel-centre.  In  Europe  the  wheel-centres  are  generally  made  of 
wrought-iron. 

Question  490.  How  are  the  tires  fastened  on  the  wheel-centres  ? 

Answer.  The  insides  of  the  tires  are  usually  turned  out  somewhat 
smaller  than  the  outside  of  the  wheel-centre.  The  tire  is  then  heated  so 
that  it  will  expand  enough  to  go  on  the  centre.  It  is  then  cooled  off, 
and  the  contraction  of  the  metal  binds  it  firmly  around  the  cast  iron  part 
of  the  wheel.  As  an  additional  security,  bolts  or  set-screws,  a a,  fig.  339, 
are  sometimes  screwed  through  the  rim  and  into  the  tire  to  prevent  it 
from  slipping  off  in  case  it  becomes  loose. 

QUESTION  491.  How  are  tires  held  on  the  wheels  in  case  the  former 
break  ? 

Answer.  In  Europe,  and  on  some  railroads  in  this  country,  locomotive 
tires  are  fastened  to  the  wheel-centres  by  what  are  called  retaining  rings. 
Fig.  340  represents  a section  of  a tire,  A,  which  is  fastened  in  this  way. 


Fig.  340.  Section  of  Tire  with  Retaining  Rings.  Scale  in.—l  in. 

The  fastenings  consist  of  flat  rings,  C C,  which  are  placed  on  each  side 
of  the  wheel  and  tire,  and  fastened  to  the  wheel-centre,  B,  with  bolts,  D. 


408 


Catechism  of  the  Locomotive. 


The  rings  have  annular  projections,  at  C C,  which  fit  into  corresponding 
grooves  in  the  tires.  In  case  the  tire  should  break,  these  rings  hold  it  in 
its  position  on  the  wheel  and  thus  prevent  an  accident. 

Question  492.  Are  there  any  standard  sizes  for  the  inside  diameters  of 
tires  ? 

Answer.  Yes.  To  avoid  the  great  inconvenience  arising  from  a diver- 
sity in  the  inside  diameters  of  tires,  the  American  Railway  Master  Mechan- 
ics’ Association  has  recommended  standard  dimensions  for  them  and  for 
the  outside  diameters  of  driving-wheel  centres.  These  are  given  in  the 
following  table  : 


Standard  Dimensions  for  Driving-Wheel  Centres  and  Tires. 


Outside  Diameter  of  Wheel- 
Centres. 

Allowance  for  Shrinkage  of 
Tire. 

Inside  Diameter  of  Tires. 

38  inches. 

0.040  inch. 

37.960  inches. 

44  “ 

0.047  “ 

43.953  44 

50 

0.053  “ 

49.947  “ 

56 

0.060  44 

55.940  44 

62 

0.066  41 

61.934  44 

66 

0.070  44 

65.930  44 

Question  493.  How  are  the  driving-wheels  fastened  on  the  axles? 

Answer.  The  hubs  are  accurately  bored  out  to  receive  the  axles,  and 
the  latter  are  turned  off  so  as  to  fit  the  hole  bored  in  the  wheel.  The 
axles  are  then  forced  into  the  wheel  by  a powerful  pressure  produced 
either  with  a hydraulic  or  screw  press,  made  for  the  purpose.  In  order  to 
prevent  the  strain  upon  the  crank-pins  from  turning  the  wheels  upon  the 
axle,  they  are  keyed  fast  with  square  keys  driven  into  grooves  cut  in  the 
axle  and  in  the  wheel  to  receive  them.  The  ends  of  these  keys  are  shown 
at  b,  fig.  339. 

Question  494.  How  are  the  cra7ik-pins  made  ? 

Answer.  They  are  made  of  wrought-iron  or  steel  and  accurately  turned 
to  the  size  required  for  the  journals  for  the  connecting-rods.  Fig.  341 
represents  one  of  the  main  crank-pins,  and  fig.  342  a back  pin  for  an 
American  type  of  engine.  The  main  pin  has  two  journals,  one,  A,  to 
which  the  main  connecting-rod  is  attached,  and  the  other,  B,  receiving 


The  Running  Gear. 


409 


the  coupling-rod.  The  back  pin  has  only  one  journal,  B , for  the  coupling- 
rod.  On  some  locomotives  the  main  connecting-rod  is  attached  to  the 
outside  journal,  B,  of  fig.  341.  The  coupling-rod  is  then  connected  to 
journals  next  to  the  wheels. 

The  collars  on  the  crank-pins  hold  the  rods  on  the  pins. 

Question  495.  How  are  the  crank-pins  fastened  to  the  wheel? 

Answer.  They  are  turned  so  as  to  fit  accurately  into  holes  which  are 
bored  in  the  wheels.  The  holes  are  usually  “ straight  ” or  cylindrical. 
The  pins  are  then  either  driven  in  with  blows  from  a heavy  weight  swung 


Crank-Pins. 


from  the  end  of  a rope,  or  else  pressed  in  with  a screw  or  hydraulic  press. 
Sometimes  the  holes  are  bored  tapered  or  conical  and  the  pins  turned  to 
the  same  form.  They  are  then  ground  in  with  emery  and  oil,  so  as  to  fit 
perfectly,  and  are  secured  by  a large  nut  and  key  on  the  inside  of  the 
wheel. 

Question  496.  What  are  the  pieces,  A A,  fig.  jjp,  between  the  spokes 
cf  the  wheels  for  ? * 

Answer.  They  are  the  counterbalance  weights,  or  counter- weights, 
which  are  put  in  the  wheels  to  balance  the  weight  of  the  crank-pins, 
connecting-rods,  and  pistons,  as  explained  in  Chapter  XIX. 

Question  497.  How  are  the  truck  wheels  made  ? 

Answer.  They  are  generally  made  of  cast  iron,  usually  in  one  piece. 
Figs.  343,  344,  and  345  represent  the  most  common  form  of  cast  iron 
wheels  which  is  used  for  locomotive  and  car  trucks.  Fig.  343  is  a view  of 
the  front  or  outside  of  a wheel,  fig.  344  of  the  back  side,  and  fig.  345  is  a 
wheel  with  a part  of  it  cut  away,  so  as  to  show  a section  of  it.  It  will  be 
seen  that  the  plates  which  form  the  centre  of  the  wheel  and  the  ribs  on 


410 


Catechism  of  the  Locomotive. 


the  back  are  curved  in  form.  They  are  made  in  this  shape  so  that  when 
the  wheel  is  cast  and  contracts  in  cooling,  the  plates  and  ribs  can  spring 
somewhat  without  being  strained  to  a dangerous  degree. 


Fig.  343.  Fig.  344. 


Fig.  345. 

Cast  Iron  Truck-Wheels. 


The  tread  of  the  wheel  is  hardened  by  a process  called  chilling , This 
is  done  by  pouring  the  melted  cast  iron  into  a mould  of  the  form 
of  the  tread  of  the  wheel.  The  mould  for  the  tread  is  also  made  of  cast 
iron,  but  being  cold,  cools  the  melted  iron  very  suddently,  and  thus 
hardens  it  somewhat  as  steel  is  hardened  when  it  is  heated  and  plunged 
into  cold  water.* 

QUESTION  498.  What  other  kinds  of  wheels  are  used  for  car  and  loco- 
motive trucks  ? 

Answer.  A variety  of  wheels  with  steel  tires  are  used  for  locomotive 
and  car  trucks.  The  wheel-centres  are  made  of  cast  iron  or  wrought-iron 
or  compressed  paper  held  between  two  wrought-iron  plates.  The  tires 
are  fastened  to  the  centres — or  they  should  be  fastened — with  some  kind 
of  retaining  rings. 

QUESTION  499.  What  is  the  shape  of  the  tread  and  flange  of  a car  and 
locomotive  wheel? 

Answer.  Fig.  846  represents  the  standard  form  for  the  treads  and 
flanges  of  car  and  locomotive  wheels  which  has  been  adopted  by  the  Mas- 
ter Car  Builders’  and  the  Master  Mechanics’  Associations. 

* It  is  only  certain  kinds  of  cast  iron  which  will  be  hardened  in  this  way,  or  will  “ chill?'  as  it 
is  called.  The  cause  to  which  this  chilling  property  is  due  is  not  known. 


Fig.  346.  Section  of  Standard  Tread  and  Flange  of  Wheel.  Full  Size, 


412 


Catechism  of  the  Locomotive. 


Question  500.  On  what  part  of  the  axle  does  the  weight  of  the  engine 
rest  ? 

Answer.  It  rests  on  what  are  called  the  journals , which  are  just  inside 
of  the  wheels.  These  journals  turn  on  brass  bearings,  called  journal-bear- 
ings, which  resist  the  friction  of  the  revolving  axle.  The  bearings  are  held 
in  cast  iron  or  cast  steel  boxes,  called  journal-boxes.  One  of  these  is 
shown  at  L,  in  fig.  339,  and  also  separately,  in  fig.  347,  in  which  C is  the 


Fig.  347.  Driving  Journal-Box. 


journal-bearing  and  d the  oil-celler.  The  latter  is  a receptacle  underneath 
the  axle  which  is  filled  with  wool  or  cotton  waste  which  is  saturated  with 
oil  for  the  purpose  of  lubricating  the  journal.  The  oil-cellar  is  held  in  its 
position  by  two  bolts,/* f,  which  pass  through  it  and  the  driving-box  casting. 
By  removing  the  bolts  the  oil-cellar  can  easily  be  removed,  and  the  box 
can  then  be  taken  off  the  axle. 

QUESTION  501.  How  are  the  boxes,  journals , and  j ournal-bearings  of 
the  truck  wheels  made  ? 

Answer.  They  are  very  similar  to  those  for  the  driving-wheels,  their 
chief  difference  being  that  those  for  the  truck  wheels  are  smaller  than 
those  for  the  driving-wheels. 

Question  502.  How  are  the  frames  for  locomotives  constructed? 

Answer.  The  frames,  32  32  32,  Plates  III,  IV  and  V.  are  made  of  bars 
of  wrought-iron  from  three  to  four  inches  thick  and  about  the  same  in 
width.  Each  frame  is  usually  made  in  two  parts,  one  at  the  back  part 
of  the  engine,  to  which  the  driving-boxes  and  axles  are  attached,  and  the 
other  at  the  front  end  to  which  the  cylinders  are  bolted.  The  back  part, 
or  main  frame,  as  it  is  called,  is  represented  in  figs.  348  and  349,  and  con- 


Fig.  349. 

Frame,  Springs  and  Driving-Boxes.  Scale  % in.=l  ft. 


414 


Catechism  of  the  Locomotive. 


sists  of  a top  bar,  H H,  to  which  pieces,  a,  a',  b,  b',  called  frame-legs , are 
welded.  Two  of  these  form  what  is  called  a jaw , which  receives  the  axle- 
box,  as  shown  in  fig.  349.  To  the  bottom  of  each  jaw  a clamp,  c,  fig.  348, 
is  bolted  to  hold  the  two  legs  together.  The  two  legs,  a and  b' , are  united 
by  a brace,  d d,  bolted  to  the  legs.  A brace,  m,  unites  the  back  end  of  the 
frame  with  the  leg,  b,  and  is  welded  to  each. 

The  front  part  of  each  frame  consists  of  a single  bar,  e,  which  is  bolted 
to  the  back  end,  as  represented  in  figs.  348  and  349,  which  show'  the  con- 
struction clearer  than  any  description  would.  The  front  bar  is  shown 
plainly  in  Plates  IV  and  V — the  back  end  only  is  shown  in  figs.  348  and 
349.  These  front  bars  extend  forward  to  the  front  end  of  the  engine,  and 
a heavy  timber,  called  a bumper-timber , extends  across  from  one  to  the 
other  and  is  bolted  to  each  of  them,  as  shown  in  Plates  III,  IV  and  V* 
This  timber  is  intended  to  receive  the  shock  or  blow  when  the  locomo- 
tive runs  against  any  object,  such  as  a car.  The  cow-catcher  or  pilot , 38 
38,  is  fastened  to  this  timber. 

The  front  bar  of  the  frames  also  has  usually  two  lugs  or  projections 
on  it,  shown  in  Plate  IV,  between  which  the  cylinders  are  attached,  The 
latter  are  securely  held  in  their  positions  by  wedges,  which  are  driven  in 
between  the  lugs  and  the  cylinder  castings. 

The  frames,  as  already  stated,  are  in  this  country  made  of  wrought-iron 
forged  bars,  and  are  accurately  planed  off  over  their  whole  surface.  In 
Europe  they  are  made  of  rolled-iron  plates. 

Question  503.  How  are  the  frames  fastened  to  the  boiler  ? 

Answer.  As  already  stated,  they  are  fastened  to  the  cylinders  with 
wedges  and  bolts,  and  as  the  cylinders  are  bolted  to  the  smoke-box,  the 
frames  are  thus  rigidly  attached  to  the  front  end  of  the  boiler.  In  order 
to  strengthen  those  portions  of  the  frames  which  extend  beyond  the  front 
of  the  smoke-box  and  to  which  the  bumper-timber  is  attached,  diagonal 
braces,  shown  in  Plates  III,  IV  and  V,  are  bolted  both  to  the  timber  and 
to  each  of  the  frames  at  their  lower  ends.  The  upper  ends  are  bolted  to 
the  smoke-box.  Other  braces  are  also  fastened  to  the  frames  and  to  the 
barrel  of  the  boiler.  The  frames  are  fastened  to  the  fire-box  by  clamps, 
10  10,  Plate  III,  called  exfansio?i  clamps.  These  clamps  embrace  the 
frames  so  that  when  the  boiler  is  heated  and  expands  the  frames  can 
slide  through  the  clamps  longitudinally.  There  are  also  usually  two 
diagonal  braces,  shown  in  Plates  III,  IV  and  V,  the  upper  ends  of  which 
are  fastened  to  the  back  end  of  the  shell  of  the  fire-box  at  about  the  level 
of  the  crown-sheet,  and  the  lower  ends  to  the  back  ends  of  the  frames. 


The  Running  Gear. 


415 


Transverse  braces  are  generally  attached  to  the  lower  part  of  the  frames, 
thus  uniting  the  two  together.  The  guide-yoke  is  also  usually  bolted  to 
the  frames  and  connected  to  the  boiler. 

Question  504.  Why  arc  the  frames  attached  to  the  shell  of  the  fire-box 
so  as  to  slide  longitudinally  through  the  faste?iings  ? 

Answer.  Because  when  the  boiler  becomes  heated  it  expands,  and  if  it 
could  not  move  independently  of  the  frames,  its  expansion  would  create  a 
great  strain  on  both  itself  and  the  frames.  The  fastenings  to  the  fire-box 
are  therefore  made  so  that  the  frames  can  move  freely  through  them 
lengthwise,  but  in  no  other  direction. 

Question  505.  How  much  more  will  a boiler  expand  than  the  frames 
in  getting  up  steam  ? 

Answer.  From  \ to  T5¥  of  an  inch. 

QUESTION  506.  Why  is  it  necessary  to  support  the  engine  on  springs? 

Answer.  Because,*  however  well  a road  may  be  kept  up,  there  will 
always  be  shocks  in  running  over  it ; these  occur  at  the  rail  joints,  and 
especially  when  the  ballasting  of  the  ties  is  not  quite  perfect.  These 
shocks  affect  the  wheels  first,  and  by  them  are  transferred  through  the 
axle-boxes  to  the  frame,  the  engine  and  the  boiler.  The  faster  the  loco- 
motive runs,  the  more  powerful  do  they  become,  and  therefore  the  more 
destructive  to  the  engine  and  road,  and  consequently  the  faster  a locomo- 
tive has  to  run  the  more  perfect  should  be  the  arrangement  of  the  springs. 

If  we  strike  repeatedly  with  a hammer  on  a rail,  the  latter  is  soon 
destroyed,  while  it  can  bear  w.ithout  damage  a much  greater  weight  than 
the  hammer  lying  quietly  on  it.  The  axles,  axle-boxes  and  wheels  strike 
like  a hammer  on  the  rails  at  each  shock,  while  the  shock  of  the  rest  of 
the  parts  of  the  engine  first  reaches  and  bends  the  springs,  but  on  the 
rails  has  only  the  effect  of  a load  greater  than  usual  resting  on  them. 

The  way  in  which  the  springs  lessen  the  injurious  effects  which  the 
weight  of  the  boiler,  etc.,  exerts  on  the  rails  will  be  made  plainer  by  an- 
other comparison. 

A light  blow  with  a hammer  on  a pane  of  glass  is  sufficient  to  shatter 
it.  If,  however,  on  the  pane  of  glass  is  laid  some  elastic  substance,  such 
as  india-rubber,  and  we  strike  on  that,  the  force  of  the  blow  or  the  weight 
of  the  hammer  must  be  considerably  increased  before  producing  the 
above-named  effect.  If  the  locomotive  boiler  is  put  in  place  of  the 
hammer,  the  springs  in  place  of  the  india-rubber,  and  the  rails  in  place  of 

*This  answer  and  much  of  the  material  referring  to  springs  has  been  translated  from  “ Die 
Schule  des  Locomotivfiihrers,”  by  Messrs.  J.  Brosius  and  R.  Koch. 


41G 


Catechism  of  the  Locomotive. 


the  glass,  the  comparison  will  agree  with  the  case  above.  From  this  con- 
sideration it  will  be  seen  how  important  it  is  to  make  the  weights  of  the 
axles,  axle-boxes,  and  wheels  as  light  as  possible. 

Question  507.  How  are  the  driving  axle-boxes  arranged  so  that  the 
weight  of  the  engine  will  rest  on  springs? 

Answer.  They  are  arranged  so  as  to  slide  up  and  down  in  the  jaws. 
Springs,  B B' , fig.  349,  are  then  placed  over  the  axle-boxes  and  above  the 
frames.  These  springs  rest  on  fl-shaped  saddles,  G G' , which  bear  on  the 
top  of  the  axle-boxes.  The  frames  are  suspended  to  the  ends  of  the 
springs  by  rods  or  bars,  g,  g' , g,  g' , called  spring-hangers..  As  the  boiler 
and  most  of  the  other  parts  of  the  engine  are  fastened  to  the  frames,  their 
weight  is  suspended  on  the  ends  of  the  springs,  which,  being  flexible, 
yield  to  the  weight  which  they  bear. 

Question  508.  How  are  the  frames  protected from  the  wear  of  the  axle- 
boxes  which  results  from  their  slidmg  up  and  down  in  the  jaws? 

Answer.  The  insides  of  the  legs,  a , a',  b,  b’ , are  protected  with  shoes  or 
wedges,  h,  h',  which  are  held  stationary,  and  the  boxes  slide  against  the 
faces  of  the  shoes,  thus  wearing  the  shoe  or  wedge,  but  not  the  frame. 

Question  509.  Why  is  one  or  both  of  the  shoes  made  wedge-shaped ? 

Answer.  They  are  made  in  that  way  so  that  when  they  become  worn, 
by  moving  one  or  both  of  them  up  in  the  jaws,  the  space  between  them  is 
narrowed  and  the  lost  motion  is  taken  up.  They  are  moved  by  the  screws, 
i,  i.  If  the  boxes  should  become  loose  from  wear,  it  would  cause  the 
engine  to  thump  at  each  revolution  of  the  wheels  or  stroke  of  the  piston. 

Question  519.  How  are  the  springs  for  the  driving-wheels  made? 

Answer.  They  are  made  of  steel  plates,  which  are  placed  one  on  top 
of  the  other.  These  plates  are  of  different  lengths,  as  shown  at  B B,  in 
fig.  349,  and  are  from  3 to  4 inches  wide,  and  ^ to  thick.  The  length 
of  the  springs  measured  from  the  centre  of  one  hanger  to  the  centre  of  the 
other  is  usually  about  3 feet. 

QUESTION  511.  What  determines  the  a7nount  which  a spring  will  bend 
under  a given  load  ? 

Answer.  The  number  of  plates,  their  thickness,  length  and  breadth, 
and  of  course  the  material  of  which  they  are  made.  This  can  be  explained 
if  we  suppose  we  have  a spring-plate  of  a uniform  thickness,  h,  and  a tri- 
angular form,  of  which  fig.  350  is  a side  view  and  fig.  351  a plan,  and  that 
it  is  clamped  fast  at  its  base,  b.  It  is  a well-known  mechanical  law  that 
any  material  of  this  form  and  under  these  conditions  will  have  a uniform 
strength  through  its  whole  length  to  support  any  load,  P,  suspended  at 


The  Running  Gear. 


417 


its  end,  and  also  that  it  will  bend  or  deflect  in  the  form  of  an  arc  of  a 
circle. 

Question  512.  How  are  locomotive  springs  usually  made? 

Answer.  In  locomotives  the  arrangement  of  springs  is  always  such 
that  they  are  either  supported  in  the  middle  and  moved  at  the  two  ends, 
or  such  that  they  are  supported  at  the  two  ends  and  loaded  in  the  middle ; 


b 


T Fig.  350. 


Diagrams  Showing  Action  of  Plate  when  Bent. 


for  our  consideration  it  is  indifferent  which  of  the  two  kinds  of  springs 
is  taken  for  the  present  illustration.  That  shown  in  plan  and  elevation 
in  figs.  352  and  353,  which  is  formed  of  a wide  plate  placed  diagonally, 
and  which  in  reality  consists  of  two  such  triangular  pieces  as  were  repre- 
sented in  fig.  351,  united  at  their  bases,  m m,  fig.  353,  and  loaded  at  two 
opposite  corners,  e and  f,  would  answer  the  requirements  mentioned  if  the 
great  breadth,  m m , were  not  an  obstacle.  This  breadth  is  obviated  by 
cutting  the  spring  into  several  strips,  a a,  b b,  c c,  d d,  . . . . /,  fig. 

353,  of  equal  width,  and  placing  these  not  side  by  side,  but  one  over  the 
other,  as  shown  in  figs.  854  and  355. 

In  order  that  the  separate  strips  and  layers  of  the  spring  so  made  may 
not  slip  out  of  place,  the  strips  a a,  b b,  etc.,  are  made  in  one  piece,  and 
all  the  plates  are  enclosed  with  a metal  strap,  F,  figs.  356,  357  and  358.  The 
plates,  instead  of  being  cut  from  a piece  like  that  represented  in  fig.  353, 
are,  however,  made  out  of  steel  of  the  proper  width,  and  the  ends,  instead 
of  being  cut  off  pointed  as  represented,  are  sometimes  drawn  out  thinner 
on  the  ends,  like  the  point  of  a chisel,  or  oftener  still  cut  off  straight,  as, 
shown  in  fig.  358. 


418 


Catechism  of  the  Locomotive. 


The  band,  F,  which  is  put  around  the  middle,  is  put  on  hot,  and  becomes 
tight  by  contracting  as  it  cools.  The  centre  of  the  spring  has  a hole  drilled 
through  it  with  a pin  or  rivet,  fig.  357  (which  shows  a cross  section 


m 


Fig’.  353. 

Diagrams  Showing  Action  of  Plate  when  Bent. 

through  the  middle  of  a spring),  to  prevent  the  plates  from  sliding  end- 
wise. The  plates  at  each  end  usually  have  a depression,  a,  fig.  359  (which 
is  a cross  section  through  the  middle  of  a plate  on  a larger  scale  than  the 


Fig.  354. 


Fig.  355. 
Springs. 


preceding  figure),  made  in  them  on  one  side,  and  a corresponding  eleva- 
tion, b,  on  the  other.  The  elevation  on  one  plate  fits  into  the  depression 
on  the  other,  and  thus  prevents  the  plates  from  slipping  sideways. 


The  Running  Gear. 


411) 


Question  513.  How  should  springs  be  curved? 

Answer.  Springs  should  be  curved  so  that  when  they  bear  the  greatest 
load  which  they  must  carry  they  will  be  straight.  If  they  are  curved  too 
much  they  are  subjected  not  only  to  a strain  which  bends  the  plates,  but 


Fig.  359. 

Driving-Springs.  Scale  % in.=l  ft. 


to  one  which  has  a tendency  to  compress  them  endwise.  Thus,  if  a spring 
like  that  represented  in  fig.  360,  is  bent  into  a half-circle,  it  is  obvious  that 


the  strain  at  the  ends  has  no  tendency  at  all  to  bend  the  plates,  but  only 
to  compress  them  endwise.  Near  the  middle  the  strain  will,  of  course, 
bend  the  spring.  In  the  one  direction  the  spring  is  flexible  and  elastic, 
• and  in  the  other  it  is  not;  and  as  the  strain  of  compression  depends  on 
the  amount  of  curvature,  the  greater  the  latter  is,  the  less  flexibility  and 
elasticity  the  spring  will  have. 


420 


Catechism  of  the  Locomotive. 


Springs  are  often  given  a double  curve,  as  shown  in  fig.  361.  This  is 
not  to  be  recommended,  because  when  a spring  bends  the  plates  must 
slide  on  each  other.  If  they  have  but  a single  curve,  they  will  do  so  and 
remain  in  contact  through  their  whole  length,  but  if  they  have  two  curves 
they  will  separate  and  therefore  “gape,”  as  it  is  called. 


Fig.  361.  Curved  Spring. 

QUESTION  514.  What  is  the  shape  of  the  band  on  the  spring  ? 

Answer.  The  bands  are  usually  made  of  the  form  shown  in  figs.  356 
and  361,  but  recently  they  have  been  made*  of  the  form  shown  in  fig.  362 


Fig.  362.  Morris’s  Spring.  Scale  % in.=l  ft. 


— that  is,  narrower  on  the  under  side  than  on  top.  This  allows  the  lower 
and  shorter  plates  to  bend  more  than  they  could  if  held  by  a wider  band, 
and  gives  them  greater  elasticity. 

Question  515.  What  is  meant  by  the  elasticity  of  a spring  ? 

Answer.  It  is  the  amount  which  a spring  will  deflect  or  bend  under  a 
given  load  without  having  its  form  permanently  changed.  If  the  bending 
is  so  great  that  the  spring  does  not  recover  its  original  form  when  the 
load  is  removed,  then  the  strain  to  which  it  is  subjected  is  said  to  exceed 
the  limits  of  elasticity , and  if  repeated  often  it  will  ultimately  break  the 
spring. 

QUESTION  516.  What  is  meant  by  the  elastic  strength  and  the  ultimate 
strength  of  a spring  ? 

Answer.  The  elastic  strength  is  the  strain  it  will  bear  without  being 

*This  is  the  invention  of  George  Morris,  and  is  manufactured  by  the  A.  French  Spring  Com- 
pany of  Pittsburgh. 


The  Running  Gear. 


421 


strained  beyond  the  limits  of  elasticity,  and  the  ultimate  strength  is  the 
strain  which  will  break  it. 

Question  517.  What  determines  the  strength  of  a spring? 

Answer.  It  depends  (1)  upon  the  material  of  which  the  spring  is 
made ; (2)  its  strength  increases  in  proportion  to  the  number  of  plates, 
and  (3)  to  their  width,  and  (4)  in  proportion  to  the  square  of  their  thick- 
ness, and  (5)  as  the  length  diminishes. 

Thus,  if  we  wanted  to  double  the  strength  of  a spring  like  that  shown 
in  figs.  350  and  351,  it  could  be  done  in  either  of  the  following  ways:  (1) 
by  making  it  of  material  twice  as  strong;  (2)  by  putting  another  plate  just 
like  it  on  top ; (3)  by  doubling  the  width  of  the  base,  b , which  would  make 
the  strength  of  the  whole  plate  twice  what  it  was  before ; (4)  by  making 
the  whole  plate  about  four-tenths  thicker,  which  would  increase  its 
strength,  as  already  stated,  in  proportion  to  the  square  of  the  thickness  as 
1.4  x 1.4=2  nearly  ; (5)  by  reducing  the  length  to  one-half  wnat  it  is  in  fig. 
350. 

Question  518.  What  determines  the  elasticity  of  a spring? 

Answer.  (1)  The  material  of  which  it  is  made ; with  the  same  material 
the  elasticity  increases  (2)  as  the  number  and  (3)  as  the  width  of  the  plates 
diminishes,  and  (4)  with  the  cube  of  the  length,  and  (5)  decreases  with  the 
cube  of  the  thickness  of  plate. 

Thus,  supposing  the  plate  in  figs.  350  and  351  to  be  -f  inch  thick  and 
the  deflection,  d , 2£  inches,  the  latter  would  be  only  half  as  much,  or  1£ 
inches  (1),  if  it  were  made  of  material  twice  as  stiff,  or  (2)  with  two  such 
plates,  or  (3)  with  one  twice  as  wide  at  the  base.  If  (4)  the  length  were 
doubled,  the  deflection  would  be  equal  to2x2x2  = 8 times  what  it  was 
before,  or  in  proportion  to  the  cube  of  the  length.  If  (5)  the  thickness 
were  doubled  the  deflection  would  be  reduced  in  the  same  proportion,  and 
would  be  only  one-eighth  of  2£  inches  or  inch. 

QUESTION  519.  What  should  be  the  proportion  of  the  plates  of  a spring 
in  relation  to  each  other  ? 

Answer.  The  lower  plates  should  diminish  regularly  in  their  lengths. 
The  reason  for  this  will  be  apparent  from  the  fact  which  has  already  been 
stated,  that  if  a triangular  plate  of  uniform  thickness  is  clamped  fast  at  its 
base,  it  will,  if  loaded  at  the  end,  be  of  uniform  strength  throughout  its 
whole  length.  It  is  immaterial  what  the  length  of  the  base  of  such  a 
triangle  is ; if  the  two  sides  are  of  equal  length  and  the  thickness  of  the 
plate  is  uniform,  not  only  its  strength,  but  the  amount  of  deflection  or 
bending  from  any  load  will  be  equal  all  through  its  length.  If,  therefore, 


422 


Catechism  of  the  Locomotive. 


we  make  a spring  by  cutting  a plate  formed  of  two  such  triangular  pieces 
united  at  their  bases  into  strips,  as  has  already  been  explained,  evidently 
the  spring  made  of  them  will  have  a uniform  strength  throughout  its 
whole  length.  As  the  strips  thus  made  diminish  in  length  regularly,  it  is 
evident  that  if  the  spring  plates  are  made  of  steel  rolled  of  the  requisite 
width,  their  length  should  be  the  same  as  that  of  those  cut  from  the  plate 
referred  to  above.  When  this  is  the  case,  the  lower  outline,  abba , fig. 
363,  of  the  spring  will,  when  the  spring  is  not  bent,  be  straight  lines. 


Fig.  363. 


F 


Fig.  364. 

Springs. 

Sometimes  the  lower  outline  of  springs  is  made  curved,  as  shown  in  fig. 
364.  This  gives  too  much  stiffness  between  the  middle,  b b,  and  the  ends, 
a,  a.  In  drawing  springs,  therefore,  it  is  best  to  lay  them  out  with  the 
plates  straight,  as  shown  in  fig.  363,  and  after  determining  the  thickness, 
drawing  a straight  line  from  a point  near  the  strap  to  the  end  of  the  long- 
est plate  will  give  the  best  form  of  the  spring  and  the  length  of  each  of 
the  plates.  It  is  necessary,  however,  to  put  a sufficient  number  of  long 
plates  in  each  spring  to  give  it  the  required  strength  next  to  the  attach- 
ment of  the  hanger.  Sometimes  one  or  more  of  these  long  plates  are 
made  thicker  than  the  rest.  The  evil  of  this  method  of  construction  will 
be  apparent,  if  it  is  remembered  that  the  greatest  permissible  deflection 
up  to  the  breaking  of  the  spring,  decreases  with  the  cube  of  the  thickness 
of  the  plate,  and  its  strength  increases  with  the  square  of  the  thickness. 
Now,  if  we  have  a spring  with  say  ten  plates  f-  inch  thick  and  one  on  top 
f inch  thick,  the  thick  plate  will  have  a strength  four  times  that  of  the 
thin  plates,  but  its  elasticity  will  be  only  one-eighth  that  of  the  thin 
plates,  and  therefore  it  will  require  eight  times  as  much  load  to  bend  it 
any  given  distance  as  is  needed  to  bend  the  thinner  plates  the  same  dis- 
tance. But  its  strength  is  only  four  times  that  of  the  thin  plates,  so  that 
for  any  given  amount  of  elasticity  the  thick  plate  must  bear  twice  as 
much  load  as  it  has  strength  to  carry.  This  shows  what  a great  mistake 


The  Running  Gear. 


423- 


is  committed  if  some  of  the  plates  are  made  thicker  than  others,  a con- 
clusion which  is  supported  by  practical  experience,  as  it  is  found  that  if 
the  top  plates  are  made  thicker  than  others,  the  thick  ones  break  most 
frequently,  which  is  the  necessary  result  of  the  supposed  strengthening  by 
increasing  the  thickness  of  the  top  plates. 

Question  520.  *How  can  we  find  by  calculation  the  elasticity  or  deflec- 
tion of  a given  steel  spring  ? 

Answer.  By  multiplying  the  breadth  of  the  plates  in  inches 

BY  THE  CUBE  OF  THEIR  THICKNESS  IN  SIXTEENTHS,  AND  BY  THE  NUM- 
BER OF  PLATES  : DIVIDE  THE  CUBE  OF  THE  SPANf  IN  INCHES  BY  THE 
PRODUCT  SO  FOUND,  AND  MULTIPLY  BY  1.66.  THE  RESULT  IS  THE 
ELASTICITY  IN  SIXTEENTHS  OF  AN  INCH  PER  TON  OF  LOAD. 

QUESTION  521.  How  can  we  find  the  span  due  to  a given  elasticity  and 
number  and  size  of  plate? 

Answer.  By  multiplying  the  elasticity  in  sixteenths  per  ton 

BY  THE  BREADTH  OF  PLATE  IN  INCHES,  AND  BY  THE  CUBE  OF  THE 
THICKNESS  IN  SIXTEENTHS,  AND  BY  THE  NUMBER  OF  PLATES  : DIVIDE 
BY  1.66,  AND  FIND  THE  CUBE  ROOT  OF  THE  QUOTIENT.  THE  RESULT 
IS  THE  SPAN  IN  INCHES. 

QUESTION  522.  How  can  we  find  the  number  of  plates  due  to  a given 
elasticity , span , and  size  of  plate? 

Answer.  By  multiplying  the  cube  of  the  span  in  inches  by 
1.66;  THEN  MULTIPLYING  the  elasticity  in  sixteenths  by  the 
BREADTH  OF  PLATE  IN  INCHES,  AND  BY  THE  CUBE  OF  THE  THICKNESS 
IN  SIXTEENTHS  : DIVIDE  THE  FORMER  PRODUCT  BY  THE  LATTER. 
The  QUOTIENT  IS  THE  NUMBER  OF  PLATES. 

Question  523.  How  can  we  find  the  working  strength — that  is,  the 
greatest  weight  it  should  bear  in  practice,  of  a given  steel-plate  spring  ? 
Answer.  By  multiplying  the  breadth  of  plates  in  inches  by 

THE  SQUARE  OF  THE  THICKNESS  IN  SIXTEENTHS.  AND  BY  THE  NUMBER 
OF  PLATES;  MULTIPLY,  ALSO,  THE  WORKING  SPAN  IN  INCHES  BY  11.3: 
DIVIDE  THE  FORMER  PRODUCT  BY  THE  LATTER.  THE  RESULT  IS  THE 
WORKING  STRENGTH  IN  TONS  (OF  2,240  POUNDS)  BURDEN. 

Question  524.  How  can  we  find  the  span  due  to  a given  strength  and 
number  and  size  of  plate  ? 


* The  following  rules  for  calculating  the  proportion  and  strength  of  steel  springs  are  from 
Clark’s  Railway  Machinery. 

+ The  span  is  the  distance  between  the  centres  of  the  spring-hangers  when  the  spring  is 
loaded. 


424 


Catechism  of  the  Locomotive. 


Answer.  By  multiplying  the  breadth  of  plate  in  inches  by 

THE  SQUARE  OF  THE  THICKNESS  IN  SIXTEENTHS,  AND  BY  THE  NUMBER 
OF  PLATES;  MULTIPLY,  ALSO,  THE  STRENGTH  IN  TONS  BY  11.3  I DIVIDE 
THE  FORMER  PRODUCT  BY  THE  LATTER.  THE  RESULT  IS  THE  WORK- 
ING SPAN  IN  INCHES. 

Question  525.  How  can  we  find  the  number  of  plates  due  to  a given 
strength,  span  and  size  of  plates  ? 

Answer.  By  multiplying  the  strength  in  tons  by  the  span  in 

INCHES,  AND  BY  11.3;  MULTIPLY,  ALSO,  THE  BREADTH  OF  PLATE  IN 
INCHES  BY  THE  SQUARE  OF  THE  THICKNESS  IN  SIXTEENTHS  : DIVIDE 
THE  FORMER  PRODUCT  BY  THE  LATTER.  THE  RESULT  IS  THE  NUMBER 
OF  PLATES. 

Question  526.  How  can  we  find  the  required  amount  of  curvature  or 
set  of  the  spring  before  it  is  loaded? 

Answer.  By  multiplying  the  elasticity,  per  ton,  in  inches,  by 

THE  WORKING  STRENGTH  IN  TONS  ; ADD  THE  PRODUCT  TO  THE  DESIRED 
WORKING  COMPASS.  THE  SUM  IS  THE  WHOLE  ORIGINAL  SET,  TO  WHICH 
AN  ALLOWANCE  OF  £ TO  f INCH  SHOULD  BE  ADDED  TO  THE  PERMA- 
NENT SETTING  OF  THE  SPRING. 

Question  527.  How  are  the  spring-hangers  attached  to  the  ends  of  the 
springs  ? 

Answer.  A great  variety  of  methods  have  been  used.  The  most  com- 
mon ones  are  those  shown  in  fig.  349,  in  which  the  hangers  consist  of 
single  bars  which  pass  through  openings  or  eyes  in  the  ends  of  the  springs, 
and  have  keys,  k k,  which  bear  on  top  of  the  springs.  Sometimes  the 
hangers  are  made  to  embrace  the  ends  of  the  springs,  as  shown  at  a a , 
figs.  356  and  358. 

The  springs  have  projections  forged  on  their  ends  to  receive  the  keys 
in  the  upper  end  of  the  hangers,  which  are  made  to  fit  the  grooves  formed 
between  the  projections. 

Question  528.  How  are  the  lower  ends  of  the  hangers  held? 

Answer.  The  front  hanger,^-,  fig.  349,  of  the  front  spring,  and  the  back 
hanger,^,  of  the  back  spring  are  attached  to  the  frame  as  shown.  Some- 
times a coiled  or  rubber  spring,  S,  is  interposed  between  the  hanger  and 
the  frame  to  give  more  elasticity.  The  hangers,  g'  g' , are  attached  to  the 
ends  of  a lever,  A A. 

QUESTION  529.  Why  are  the  ends,  g' g' , of  the  springs  attached  to  the 
lever  ,*  A A? 


* This  lever  is  called  an  equalizing  lever  or  beam , or,  more  briefly,  an  equalizer. 


The  Running  Gear. 


425 


Answer.  Because  if  there  is  a spring  for  every  axle  and  the  hangers 
are  fastened  to  the  frames,  then  evidently  the  locomotive  has  as  many 
points  of  support  as  it  has  axle-boxes.  Every  shock  from  the  rails  is 
transferred  through  the  wheel  and  the  axle  to  the  nearest  axle-box  and 
the  spring  belonging  to  it,  and  the  latter  must  be  made  strong  enough  to 
receive  and  dispose  of  the  whole  of  it.  If  the  adjacent  hangers,  g'  g',  fig. 
349,  of  the  adjoining  springs,  B and  B\  are  connected  by  an  equalizing 
lever,  A A,  which  turns  on  the  fixed  point,  C,  then  the  shock  which  affects 
one  wheel  will  be  transferred  first  to  the  spring,  B,  over  it.  From  this 
spring  a part  of  the  shock  will  be  transferred  to  the  frame  by  the  hanger, 
g,  and  a part  by  the  hanger,^',  to  the  equalizer,  A,  which  will  transfer  the 
pressure  to  the  adjoining  spring,  B' . If,  by  some  uneveness  of  the  road 
or  a powerful  oscillation  of  the  locomotive,  a spring  is  momentarily 
burdened,  the  equalizer  thus  causes  the  next  wheel  to  receive  part  of  this 
load. 

The  advantages  of  this  arrangement  are  evident : since  the  springs  have 
to  receive  only  a part  of  the  shocks,  they  can  be  made  less  strong  and 
therefore  more  flexible.  The  danger  of  running  off  the  track  and  that  of 
breaking  axles,  springs  and  hangers,  is  therefore  reduced  by  the  use  of 
equalizing  levers. 

Question  530.  How  are  the  equalizing  levers  constructed ? 

Answer.  They  are  made  of  wrought-iron,  and  are  supported  in  the 
centre  by  a fulcrum,  C,  fig.  349,  which  is  fastened  to  the  frame  or  boiler 
or  both.  The  spring  hangers,  g'  g\  are  usually  attached  to  the  levers  by 
eyes  and  keys.  Sometimes  eyes  are  made  in  the  lever,  as  shown  in  fig. 
349,  and  the  hanger  is  inserted  into  the  eye  and  held  either  with  a key,  as 
shown,  or  else  with  projections  which  are  forged  on  the  hanger  below  the 
lever.  In  other  cases  the  hangers  are  made  with  an  eye  which  embraces 
the  end  of  the  lever,  as  explained  in  answer  to  Question  527. 

Question  531.  How  is  the  distribution  of  weight  of  the  engine  affected 
by  the  equalizing  levers  ? 

Answer.  The  effect  of  the  equalizing,  levers  is  to  distribute  the  weight 
equally  on  all  of  the  driving-wheels.  This  will  be  apparent  if  it  is  observed 
that  the  weight  suspended  from  each  of  the  spring-hangers  of  each  spring 
in  fig.  348  must  be  the  same  ; for  if  the  weights  in  the  two  hangers,  g'  and 
gf,  were  unequal,  then  the  end  of  the  spring  which  supports  the  heaviest 
weight  would  be  drawn  down  until  the  pressure  was  equalized.  If  the 
weights  suspended  from  the  two  hangers,^'  and^',  attached  to  the  equaliz- 
ing lever  were  unequal,  then  the  one  supporting  the  greatest  load  would 


426 


Catechism  of  the  Locomotive. 


draw  up  its  end  of  the  equalizer  until  the  weights  were  again  in  equilib- 
rium. 

Another  effect  of  equalizing  levers  is  that  each  side  of  the  locomotive  is 
supported  in  such  a way  that  the  action  is  the  same  as  it  would  be  if  it 
was  supported  on  one  point.  If,  for  example,  we  have  a heavy  beam,  say 
a piece  of  timber  like  that  shown  by  A B,  fig.  365,  suspended  at  one  point 


Fig.  365. 


C,  in  its  centre,  to  the  middle,  a , of  a long  spring,  D E,  the  ends  of  which 
rest  on  two  supports,  F and  G,  it  is  evident  that  if  the  point  of  suspension 
is  at  the  middle,  C,  of  the  beam,  and  a of  the  spring,  the  weight  of  the 
beam  will  rest  equally  on  the  two  supports,  .A  and  G,  and  that  the  ends  of 
the  beam  can  move  up  or  down  or  vibrate  about  the  point  of  suspension, 
C,  without  affecting  the  distribution  of  weight  on  the  supports,  F and  G~ 
If,  now,  the  timber  is  suspended  from  three  points,  its  middle,  C,  and  two 
ends,  A and  B,  as  shown  in  fig.  366,  the  ends,  A and  B,  being  attached  to 
the  ends  of  the  springs,  b c and  d e , the  latter  resting  on  the  supports,  F 


The  Running  Gear. 


427 


and  Gy  and  connected  at  their  opposite  ends  to  an  equalizer , f g,  whose 
fulcrum  is  at  a,  it  is  evident  that  each  of  the  end  hangers,  b A and  e B, 
must  support  one-half  of  that  part  of  the  weight  of  the  timber  between  it 
and  the  middle,  C,  and  that  the  centre  hanger,  a C,  must  support  one-half 
the  weight  between  the  middle  and  each  of  the  two  ends.  Thus,  the 
hanger,  b A,  must  support  one-half  the  weight  of  the  timber  between  A 
and  C,  and  e B must  support  one-half  of  that  between  B and  C ; in  other 
words  the  end  hangers  would  each  sustain  one-fourth  of  the  weight  of 
the  timber  and  the  middle  one-half  of  its  weight.  If  the  weight  of  the 
timber  is  1,000  lbs.,  the  end  hangers  would  each  sustain  250  and  the  mid- 
dle one  500  lbs.  The  weight  of  the  middle  of  the  timber  is  hung  on  the 
equalizer ,fg,  and  one-half,  or  250  lbs.,  of  it  is  thus  transferred  to  each  of 
its  ends,  f and  g,  and  thence  to  the  hangers,  f c and  g d,  and  thus  to  the 
springs,  so  that  the  ends,  c and  d , of  the  springs  each  sustain  a weight  of 
250  lbs. ; therefore,  as  the  opposite  ends  also  sustain  the  same  weight,  it 
is  evident  that  each  of  the  springs  bears  a total  load  of  500  lbs.,  or  one- 
half  of  the  weight  of  the  timber.  If  the  ends  of  a timber  supported  as 
shown  in  fig.  366,  are  moved  up  or  down  about  the  centre  point  of  suspen- 
sion, it  is  evident  that  the  distribution  of  weight  would  not  be  affected 
any  more  than  it  was  in  fig.  365  by  a similar  movement,  because  if  the 
ends  of  the  timber  move  as  shown  by  the  dotted  lines  around  the  centre 
point  of  suspension,  C,  the  end,  A , will  ascend  as  much  as  B descends. 
The  same  thing  is  true  of  the  ends,  b and  e,  of  the  springs  and  of  their 
opposite  ends,  c and  d,  and  also  of  the  ends  of  the  equalizer,  so  that  when 
the  timber,  springs  and  equalizer  are  in  the  position  shown  by  the  dotted 
lines,  it  is  in  equilibrium,  just  as  it  was  when  the  timber  was  horizontal ; 
and  therefore  the  weight  on  the  supports  is  the  same  in  both  cases,  thus 
showing  that  the  load,  A B,  can  move  about  the  centre  of  suspension 
when  supported  as  shown  in  fig.  366,  as  freely  as  it  can  if  arranged  as 
shown  in  fig.  365.  It  therefore  follows  that  in  the  distribution  of  the 
weight  of  each  side  of  the  locomotive  on  the  wheels  and  on  the  track,  it 
may  be  regarded  the  same  as  though  it  was  supported  at  one  point,  which 
is  the  fulcrum  of  the  equalizing-lever. 

Question  532.  What  advantage  results  from  supporting  the  weight  of 
the  back  part  of  the  locomotive  on  two  points  ? 

Answer.  If  the  back  part  of  the  locomotive  rests  on  only  two  points 
and  the  front  end  on  the  centre  of  the  truck,  then  the  whole  weight  of  the 
engine  will  be  sustained  on  three  points.  Now  it  is  a well-known  fact 
that  any  tripod,  like  that  on  which  an  engineer’s  level  is  mounted,  or  a 


428 


Catechism  of  the  Locomotive.. 


three-legged  stool,  will  adjust  itself  to  any  surface,  however  uneven,  and 
stand  firmly  in  any  position ; whereas  if  there  are  more  than  three  points 
of  support,  as  a four-legged  stool,  if  they  are  all  in  the  same  plane,  the  sur- 
face on  which  they  rest  must  be  a plane,  otherwise  some  of  them  will  not 
touch.  All  railroad  tracks  have  inequalities  of  surface,  and  therefore  it  is 
of  the  utmost  importance  that  a locomotive  should  be  able  to  adjust  itself 
on  Its  points  of  support  to  any  unevenness  of  the  track  on  which  it  must 
run.  This  is  possible  only  when  the  weight  rests  on  three  points  of 
support. 

Question  533.  How  is  the  truck  constructed ? 

Answer.  As  has  already  been  explained,  trucks  usually  have  two  pairs 
of  wheels.*  These  are  attached  to  a frame,  75  75,  Plates  III,  IV  and  V. 
The  axles  have  boxes,  called  truck-boxes , and  brass  bearings  similar  to 
those  used  on  the  driving-axles.  These  boxes  work  in  jaws,  also  similar  to 
those  on  the  main  engine  frame,  excepting  that  they  have  no  attachment 
to  prevent  them  from  being  worn  by  the  motion  of  the  boxes  up  and 
down  in  the  jaws.  Fig.  367  is  a longitudinal  section,  fig.  368  a plan,  and 
fig.  369  a transverse  section  f of  a truck.  The  frame,  C D E F,  fig.  368, 
shown  also  at  h'  //,  figs.  367  and  369,  is  of  rectangular  form,  and  is  forged 
in  one  piece.  The  legs,//,  which  form  the  jaws  for  the  boxes  are  bolted 
to  the  frame  as  shown  in  fig.  367.  To  the  lower  end  of  these  legs  a brace, 
g g g,  is  bolted,  which  ties  them  together.  On  each  side  of  the  truck  one 
spring,  M M , is  placed  under  the  frame  and  in  the  reverse  or  inverted 
position  to  that  of  the  driving-springs  shown  in  fig.  349.  A pair  of 
equalizing  levers,  G G,  is  placed  on  each  side  of  the  truck,  one  lever  on 
the  inside  of  the  frame  and  the  other  on  the  outside,  as  shown  in  the  plan. 
Referring  to  fig.  367,  and  it  will  be  seen  that  the  ends  of  these  equalizers 
rest  on  the  top  of  the  truck-boxes,  and  the  springs  are  attached  to  the 
levers,  at  i i,  by  the  hangers,  j j.  The  truck-frame  rests  on  the  top  of  the 
spring-strap,  N.  It  is  evident  that  this  arrangement  of  spring  and 
equalizer  operates  in  the  same  way  as  that  employed  for  the  driving- 
wheels  in  distributing  the  weight  on  each  of  the  wheels,  and  that  the  truck- 
frame  is  supported  on  two  points,  k k , figs.  368  and  369.  The  weight  of 
the  front  end  of  the  engine  rests  on  a cast  iron  centre-plate , H.  This  is 
sometimes  bolted  rigidly  to  transverse  bars,  m m , m m,  figs.  368  and  369, 
which  are  fastened  to  the  sides  of  the  truck-frame.  The  engravings  show 

* In  some  rare  cases  three  pairs  of  wheels  are  employed  for  locomotive  trucks.  Six- wheeled 
trucks  are  very  commonly  used  under  passenger  cars. 

t The  sections  are  both  shown  through  the  centre  of  the  truck. 


Fig.  369. 

Four-Wheeled  Truck.  Scale  in.=l  ft. 


430 


Catechism  of  the  Locomotive. 


what  is  called  a swing-motion  truck.  In  this  the  centre-plate  is  suspended 
from  the  transverse  bars  by  links,  L L,  L Z,  so  that  it  can  swing  or  oscil- 
late transversely  to  the  rails.  These  links  are  suspended  from  the  pins, 
//,//,  which  pass  through  the  bars,  m m , m m,  and  the  centre  casting  or 
centre-plate,  H,  rests  on  other  pins,  l'  l' , which  pass  through  the  lower 
ends  of  the  links.  The  dotted  lines,  L a,  L b,  and  the  arcs,  a b,  a b,  show 
how  the  centre-plate,  H>  swings  on  the  links.  The  centre-pin,  S,  some- 
times has  a key  underneath  the  centre-plate.  This  key  is  intended  to 
prevent  the  engine  from  “jumping”  off  of  the  truck  on  a rough  track  or 
in  case  of  accident.  The  annular  cavity  in  the  top  of  the  centre-plate  and 
the  projection  which  fits  into  it  are  intended  to  receive  the  strain  which 
otherwise  would  bear  against  the  centre-pin  and  would  be  liable  to  break 
or  bend  it. 

From  this  description  it  will  be  seen  that  while  the  truck-frame  rests  on 
two  points,  k and  k , the  weight  of  the  engine  is  supported  by  the  centre- 
plate  of  the  truck.  As  the  back  part  of  the  engine  rests  on  substantially 
the  centres  of  the  two  equalizers,  this  distribution  of  the  weight  fulfills 
the  conditions  of  the  tripod,  or,  as  it  has  been  called,  the  “three-legged 
principle." 

Question  534.  How  are  “pony"  or  Bissell*  trucks  with  a single  pair 
of  wheels  constructed ? 

Answer.  A plan  of  such  a truck, g s h,  with  its  details  omitted,  is  shown 
in  fig.  338.  Figs.  370,  371  and  372  represent  a truck  of  this  kind  with  all 
its  parts ; 370  is  a longitudinal  section,  371  a plan,  and  372  transverse 
section.  It  consists  of  a rectangular  frame,  C D E F,  fig.  371,  to  which 
the  axles  are  attached.  As  explained  in  answer  to  Question  485,  it  also 
has  an  A-shaped  frame,  which  is  bolted  to  the  back  part  of  the  rectangu- 
lar frame.  The  apex  of  this  A-shaped  part  is  connected  to  the  main 
frame  of  the  locomotive  by  a pin,  s,  about  which  the  truck  can  turn.  The 
A-shaped  portion  of  the  frame  is  indicated  by  the  letters,  r s t.  Such 
trucks  have  swing-bolsters,  H , similar  to  those  used  on  four-wheeled 
trucks.  They  are  suspended  from  links,  L L , whose  ends  swing  in  arcs  of 
circles  indicated  by  the  dotted  lines,  a b. 

Question  535.  How  are  the  king-bolts  of  pony-trucks  arranged  ? 

Answer.  The  front  king-bolt,  K K,  figs.  370  and  372,  is  held  in  a cast- 
ing, B B,  which  is  bolted  to  the  engine  frame.  The  king-bolt  bears  on 
the  swing-bolster,  H.  In  some  pony-trucks  this  king-bolt  is  a solid  bolt 
or  pin,  like  that  shown  in  figs.  367  and  368.  In  other  cases  it  has  been 


* So  named  after  the  inventor,  Louis  Bissell. 


The  Running  Gear. 


431 


Bissell  or  Pony  Truck.  Scale  in.— 1 ft. 


432 


Catechism  of  the  Locomotive. 


found  desirable  to  connect  trucks  of  this  kind  with  the  front  driving- 
wheels  by  an  equalizing  lever,  and  the  king-bolt  is  then  made  hollow,  as 
shown  in  figs.  370,  371  and  372. 


Fig.  372.  Bissell  or  Pony  Truck.  Scale  in.=l  ft. 


Question  536.  Why  are  pony  trucks  connected  to  the  driving-wheels  by 
equalizing-levers  ? 

Answer.  This  is  done  for  very  much  the  same  reason  that  driving- 
wheels  are  connected  together  in  this  way,  as  was  explained  in  answer  to 
Q uestion  529.  The  connection  of  a pony  truck  with  the  driving-wheels 
of  a locomotive  is  the  invention  of  the  late  William  S.  Hudson,  who 
patented  the  plan  in  1864.  In  his  specification  he  said  that  “ in  practice 
irregularities  more  or  less  serious  occur  at  nearly  every  joint  or  junction 
of  the  ends  of  the  rails,  and  at  certain  points  in  a railroad  track,  as  in 
passing  switches  and  across  tracks,  and  especially  in  passing  over  small 
obstacles  or  defects  in  the  road,  the  inequality  in  the  load  which  is  thrown 
upon  the  several  wheels  becomes  very  great  unless,  in  addition  to  the 
rise  of  the  springs,  provision  is  made  by  introducing  equalizing-levers  in 
some  manner  to  induce  a unity  of  action  between  each  pair  of  wheels  and 
some  other  pair.” 

Question  537.  How  are  equalizing-levers  arranged  to  connect  pony 
trucks  with  the  driving-axles  of  locomotives  ? 


The  Running  Gear. 


433 


Answer.  Usually  one  equalizing-lever,  0 P Q,  figs.  370  and  371,  is 
placed  in  the  middle  of  the  engine  instead  of  one  on  each  side,  as  is  the 
ordinary  practice  with  driving-wheels.  This  lever  has  a fulcrum  at  P, 
which  is  attached  to  the  engine  frame.  The  front  end,  O,  of  the  lever  is 
supported  in  an  eye,  c c (shown  clearly  in  fig.  370),  which  is  formed  in  the 
lower  end  of  the  centre-pin,  S.  This  pin  passes  through  the  hollow  king- 
bolt, K K,  and  is  supported  by  a pair  of  nuts  screwed  on  the  upper  end, 
and  which  bear  on  top  of  the  king-bolt.  The  king-bolt  can  slide  vertically 
in  the  casting,  BP.  A is  the  front  driving-axle,  and  d d d represents  one- 
half  of  the  periphery  of  one  of  the  front  driving-wheels,  and  e e one-half 
of  the  driving-wheel  springs.  A transverse  equalizing-lever,  h j,  figs.  371 
and  372,  is  suspended  by  hangers,  k k , to  the  front  ends  of  the  driving- 
wheel  springs,  and  the  back  end,  Q, , of  the  lever,  O P Q,  is  suspended  to 
the  centre,  z,  of  the  lever,  h ij , by  a hanger,  m.  It  is  obvious  that  if  one 
or  both  of  the  front  driving-wheels  should  roll  over  any  object,  or  a high 
place  in  the  track,  so  as  to  be  raised  up  and  thus  compress  one  or  both  of 
the  springs,  e e , that  this  action  would  produce  an  upward  tension  on  the 
transverse  lever,  h i j,  the  hanger,  in,  and  the  back  end,  Q,  of  the  lever, 
O P Q,  and  this  would  exert  a downward  pressure  on  the  front  end,  O, 
which  would  be  transferred  by  the  centre-pin,  S,  to  the  top  of  the  king- 
bolt, K K,  and  by  it  to  the  bolster,  H,  which  is  suspended  by  links,  L L, 
to  the  truck  frame.  Any  undue  weight  resting  on  one  or  both  of  the 
driving-wheels  would  thus  be  transmitted  to  the  truck,  and  a reverse  action 
will  occur  if  the  truck  wheels,  W W,  bear  any  undue  weight. 

Question  538.  How  does  such  a truck  adjust  itself  to  the  curvature  of 
the  track  ? 

Answer.  The  two  centre-pins,  5 and  s,  are  both  attached  to  the  loco- 
motive on  its  centre-line,  represented  by  U V,  fig.  371,  and  they  cannot 
move  away  from  that  line.  If  the  truck  wheels,  W W,  encounter  a curve 
they  must  move  sideways  in  relation  to  the  engine.  This  they  are  enabled 
to  do  by  reason  of  the  bolster,  H,  being  suspended  from  the  truck  frames 
by  the  links,  L L,  fig.  372.  The  lower  ends  of  these  links  can  swing  in 
relation  to  the  upper  ones,  as  indicated  by  the  arcs,  a b and  b a,  in  fig.  369, 
or  the  upper  ends  can  move  in  relation  to  the  lower  ones,  as  shown  in  fig. 
372.  When  the  front  end  of  the  locomotive  enters  a curve,  the  truck 
wheels  and  the  frame  move  laterally  and  carry  the  upper  ends  of  the  links 
toward  a a or  b b,  fig.  372,  according  to  the  direction  of  inclination  of  the 
curve,  and  the  bolster,  H,  centre-pin,  S,  and  king-bolt,  K K,  all  retain 
their  central  position  in  relation  to  the  engine.  When  the  truck  wheels 


434 


Catechism  of  the  Locomotive. 


move  laterally  their  axle,  instead  of  being  parallel  to  the  driving-axle, 
becomes  inclined  to  it,  as  shown  by  the  dotted  centre  lines,  g t and  c d, 
fig.  338,  and  on  a curve  the  position  of  the  centre  line  of  the  truck-axle 
approximates  to  that  of  a radius  of  a curve  on  which  the  engine  is  moving 
or  standing. 

Question  539.  How  are  the  springs  of  a pony  truck  arranged? 

Answer.  In  the  truck  shown  by  figs.  370,  371  and  372,  spiral  springs, 
M M,  are  used.  These  are  placed  underneath  the  frames,  as  shown,  and 
H -shaped  yokes,  G G,  G G,  rest  on  top  of  the  axle-boxes,  and  are  coupled 
to  a cup-shaped  casting  under  the  springs,  and  on  which  they  rest.  The 
form  of  these  yokes  is  shown  partly  by  dotted  lines  in  fig.  370. 

Question  540.  What  advantage  does  the  use  of  a pony  truck  give  over 
one  with  four  wheels  ? 

Answer.  It  permits  of  the  front  driving-wheels  being  placed  closer  to 
the  cylinders  than  is  possible  when  one  pair  of  the  truck  wheels  is  behind 
the  cylinders,  as  it  usually  is  when  a four-wheeled  truck  is  used.  If  the 
driving-wheels  are  located  nearer  to  the  cylinders  they  will  bear  a larger 
proportion  of  the  weight  of  the  engine  than  they  do  if  they  are  further 
back. 


CHAPTER  XXI. 


MISCELLANEOUS. 

Question  541.  What  is  a sand-box  of  a locomotive , and  how  is  it  con- 
structed? 

Answer.  A sand-box,  39,  Plates  III  and  IV,  is  usually  a cylindrical 
receptacle  which  is  made  of  sheet  iron  with  a cast  iron  base  and  top.  It 
is  generally  placed  on  top  of  the  boiler  and  is  intended  to  carry  a supply 
of  dry  sand,  which  is  scattered  on  the  rails  in  front  of  the  driving-wheels 
when  the  latter  are  liable  to  slip.  This  is  done  by  pipes,  40,  Plate  III,  one 
on  each  side  of  the  engine.  They  lead  from  the  sand-box  to  within  a few 
inches  of  the  rail.  At  the  upper  end  and  inside  the  sand-box  they  each 
have  a valve  which  is  operated  by  a lever  connected  to  the  cab  by  a rod 
so  that  the  locomotive  runner  can  open  or  close  the  valve  at  pleasure. 
The  sand-box  has  an  opening  on  top  through  which  the  sand  is  supplied 
to  the  box.  This  opening  has  a loose  cover  to  exclude  rain  and  dirt  from 
the  sand. 

QUESTION  542.  What  is  the  bell , 41,  Plates  III  and  IV,  for  ? 

Answer.  It  is  used  for  giving  signals  of  the  starting  or  approach  of  the 
engine.  It  also  is  located  on  top  of  the  boiler  and  is  usually  hung  on  a 
cast  iron  frame  and  rung  with  a rope,  shown  in  Plate  III,  connecting  it 
with  the  cab.  Locomotive  bells  usually  weigh  from  50  to  100  lbs. 

Question  543.  What  is  the  signal-gong? 

Answer.  It  is  a gong-bell  with  a hammer  or  clapper  attached  to  it,  and 
fastened  usually  to  the  under  side  of  the  roof  of  the  cab.  The  train  bell- 
cord  is  connected  to  the  hammer,  by  which  the  bell  can  be  rung  from  any 
part  of  the  train  to  signal  to  the  engineer  to  start  or  stop  the  engine. 

Question  544.  What  is  a locomotive  head-light? 

Answer.  It  is  a large  lamp,  35,  Plates  III  and  IV,  placed  in  front  of 
the  locomotive  to  signal  its  approach  at  night  and  also  to  illuminate  the 
track  for  the  locomotive  runner. 

Question  545.  How  is  a head-light  constructed ? 

Answer.  The  lamp  has  what  is  called  an  Argand  burner;  that  is,  a 
burner  with  a hollow  cylindrical  wick  through  the  centre  of  which  a cur- 


436 


Catechism  of  the  Locomotive. 


rent  of  air  circulates  which  thus  supplies  the  flame  with  a larger  quantity 
of  air  than  is  possible  if  the  air  can  come  in  contact  with  the  burner  only 
on  the  outside.  The  result  is  that  the  combustion  of  an  Argand  burner 
is  much  more  brilliant  than  that  of  ordinary  burners.  In  order  to  throw 
all  the  light  on  the  track  the  burner  is  placed  inside  of  a concave  reflector, 
ab  c,  fig.  373,  which  is  of  a parabolic  form.  One  of  the  peculiarities  of 


Fig.  373.  Head- Light  Reflector. 


this  form  of  reflector  is  that  if  a light  is  placed  in  its  focus,  f,  the  rays 
will  be  reflected  from  its  surface  in  parallel  lines.  Thus,  let  a b c,  fig.  373, 
represent  a section  of  such  a reflector.  Now,  if  a light  be  placed  in  the 
focus,  f,  the  rays  will  strike  against  the  reflector  in  the  direction  of  the 
dotted  lines,  f \,f  2 . . . f 9,  etc.,  and  be  reflected  in  straight  hori- 

zontal lines,  1 x,  2 x,  3 x,  etc.,  and  thus  be  thrown  directly  in  front  of  the 
engine.  The  reflectors  are  usually  made  of  copper  and  plated  with  silver. 

The  lamps  and  reflectors  for  head-lights  are  enclosed  in  a rectangular 
case  which  is  placed  on  top  of  the  smoke-box,  or  is  supported  on  two 


Miscellaneous. 


43? 


brackets  bolted  to  the  front  of  it.  On  these  brackets  a wooden  shelf  is 
fastened  on  which  the  head-light  rests. 

QUESTION  546.  What  are  the  running-boards  and  hand-rails  ? 

Answer.  The  running-boards  are  narrow  platforms,  made  of  wood  or 
iron,  56  56,  Plate  III,  placed  on  each  side  of  the  boiler  to  enable  the  loco- 
motive runner  or  fireman  to  go  from  the  cab  to  the  front  end  of  the 
engine  when  it  is  running.  The  hand-rails,  57  57,  are  brass  cr  iron  pipes 
attached  to  the  top  of  the  boiler  and  extending  from  the  cab  to  the  smoke- 
box,  and  are  placed  there,  as  their  name  indicates,  for  persons  on  the 
running-board  to  take  hold  of. 

QUESTION  547.  What  provision  is  made  for  removing  from  the  track 
obstacles  such  as  cattle , fallen  rocks,  etc.,  which  may  be  in  front  of  locomo- 
tives ? 

Answer.  What  is  called  a cow-catcher  or  pilot,  38,  Plates  III  and  IV, 
is  attached  to  the  front  of  the  locomotive.  This  is  usually  made  of  wood, 
and  consists  of  a triangular  frame  at  the  bottom,  which  is  supported  so 
that  it  is  a few  inches  above  the  tops  of  the  rails.  Straight  pieces  of 
wood  of  about  2£  x4  inches  section  are  fastened  to  this  frame  and  also  to 
a horizontal  piece  which  is  bolted  to  the  bumper-timber.  These  pieces 
when  arranged  in  this  way,  and  only  a few  inches  apart,  give  to  the  cow- 
catcher a peculiar  curved  form — somewhat  resembling  that  of  the  mould- 
board  of  a plow — which  is  very  well  adapted  for  throwing  any  obstacles 
from  the  track.  Sometimes  these  pieces  are  placed  horizontally  instead 
of  being  inclined  up  and  down.  Cow-catchers  are  also  in  some  cases 
made  of  round  iron  bars  or  angle  iron.  They  are  always  bolted  securely 
to  the  bumper-timber  and  strengthened  by  strong  iron  braces  attached  to 
the  bottom  frame  at  the  front  and  back.  These  braces  are  usually  fastened 
at  the  other  end  to  the  bumper-timber,  but  are  sometimes  attached  to  the 
bed-plates  of  the  cylinders. 

There  is  also  usually  a strong  pushing-bar,  79,  Plate  4,  attached  with  a 
bolt  and  hinged  joint  to  the  bumper-timber.  This  is  shown  in  Plates  IV 
and  V in  the  position  it  occupies  when  not  in  use.  It  is  used  in  pushing 
cars,  as  very  often  there  is  not  room  for  the  pilot  under  the  end  of  the 
car.  In  using  it,  it  is  raised  up,  and  the  front  end  is  then  coupled  to  the 
draw-head  of  the  car. 

Iron  plates  and  scrapers  are  often  attached  to  the  pilots  in  winter  to 
remove  snow  from  the  track. 

QUESTION  548.  What  is  the  foot-board  or  foot-plate  of  a locomotive  ? 

Answer.  It  is  a wrought  or  cast  iron  plate,  95,  Plate  IV,  which  extends 


438 


Catechism  of  the  Locomotive. 


across  and  rests  upon  the  two  frames  at  the  back  part  of  the  locomotive 
and  behind  the  boiler,  and  on  which  the  locomotive  engineer  and  fireman 
stand.  It  also  unites  the  two  frames  very  securely,  and  furnishes  an 
attachment  for  the  draw-bar. 

QUESTION  549.  What  other  purpose  is  the  foot-board  sometimes  made 
to  serve  ? 

Answer.  It  is  sometimes  made  much  heavier  than  is  necessary  for 
strength  in  order  to  increase  the  weight,  and  thus  the  adhesion,  on  the 
driving-wheels.  It  is  a fact  often  not  suspected  that  any  weight  placed 
on  the  back  end  of  an  ordinary  locomotive  will  increase  the  load  on  the 
driving-wheels  by  an  amount  considerably  greater  than  that  of  the  weight 
itself.  The  reason  of  this  is  that  the  locomotive  rests  on  the  centre  of  the 
truck  and  the  centres  of  the  equalizers,  and  therefore  the  weight,  if  applied 
to  the  back  end  of  the  engine,  gains  considerable  leverage.  This  will  be 
clear  if  we  take  a beam,  A B , and  rest  it  on  two  supports,  m and  n.  fig. 

je C - -—-Hi 


t 

I 

I 


Fig.  374.  Diagram  Showing  Effect  of  Weight  on  Foot-Boards. 


374. . If,  now,  we  put  a weight,  W,  on  the  end,  overhanging  the  point  of 
support,  the  weight  which  will  rest  on  n will  be  equal  to  that  of  W multi- 
plied by  its  distance,  C,  from  m and  divided  by  the  distance,  D,  between  m 
and  n.  Thus,  if  a foot-board  weighs  1,000  lbs.,  and  its  centre  of  gravity 
is  5^  feet  behind  the  centre  of  the  equalizer,  and  the  latter  14  feet  from 
the  centre  of  the  truck,  then  the  weight  thrown  on  the  driving-wheels  will 
be  equal  to 

1,000  x 19£ 

= 1,393  lbs. 

14 

The  same  thing  is,  of  course,  true  of  any  other  weight  placed  on  the  back 
end  of  the  engine. 


Miscellaneous. 


439 


QUESTION  550.  What  are  the  “ wheel-guards  ” of  a locomotive  ? 

Answer.  They  are  sheet  iron  covers,  61  61,  Plate  III,  over  the  upper 
half  of  the  periphery  or  tread  of  the  wheels,  and  are  placed  there  to  protect 
the  engine  from  the  dirt  and  mud  which  adhere  to  the  wheels,  and  are 
then  thrown  off  on  the  machinery  by  the  centrifugal  force. 

QUESTION  551.  What  are  “ check  ” or  “ safety  chains  ” ? 

Answer.  There  are  two  kinds  of  such  chains,  the  one,  78,  Plates  III  and 
IV,  attached  to  the  trucks  and  frames  of  the  locomotive  and  the  tender. 
The  object  of  these  chains  is  to  prevent  the  trucks  from  turning  around 
and  getting  crosswise  of  the  track  if  they  should  leave  the  rails.  The 
other  kind  of  safety  chains,  50,  Plates  III  and  IV,  connect  the  engine 
to  the  tender,  so  that  in  case  the  draw-bar  or  coupling-pins  should  break, 
the  engine  and  tender  will  not  separate.  Great  care  should  be  exercised 
to  attach  the  truck  chains  so  that  the  fastenings  will  be  strong  enough  to 
resist  the  strains  to  which  they  will  be  subjected  in  case  the  trucks  run  off 
the  track.  The  grossest  carelessness  and  ignorance  are  often  shown  in 
the  construction  of  these  parts. 

QUESTION  552.  Where  should  steps  be  placed  on  loco?notives  ? 

Answer.  Steps  should  be  attached  to  the  back  end  of  the  locomotive, 
as  shown  by  101,  Plates  III,  IV  and  V,  to  enable  the  men  to  get  on  and 
off  the  foot-board.  Such  steps  are  usually  made  too  small,  so  that  those 
who  use  them  are  liable  to  miss  their  foothold,  especially  at  night.  To 
guard  against  this  they  should  be  made  of  more  liberal  size  than  they 
usually  are  made.  Steps  should  also  be  attached  to  the  pilots  of  locomo- 
tives for  men  to  stand  on  in  coupling  the  locomotives  to  cars.  Without 
such  steps  men  must  often  be  exposed  to  great  danger  in  coupling  cars  to 
the  front  end  of  an  engine. 


CHAPTER  XXII. 


FRICTION  AND  LUBRICATION. 

Question  553.  What  is  meant  by  friction  ? 

Answer.  Friction  is  the  resistance  between  two  bodies  in  contact  which 
opposes  the  sliding  of  the  one  on  the  other.  Thus,  if  a brick  is  placed  on 
a board  with  a slight  inclination,  it  will  not  slide  because  the  friction 
between  them,  or  the  resistance  opposed  to  motion,  is  greater  than  the 
force  exerted  by  the  weight  of  the  brick  to  move  it  downward.  If,  how- 
ever, the  inclination  of  the  board  is  increased  sufficiently  so  that  a larger 
proportion  of  the  weight  of  the  brick  urges  it  downward,  then  the  friction 
will  be  overcome,  and  it  will  slide.  When  the  brake-blocks  of  a car  are 
pressed  against  the  wheels,  they  produce  friction,  which  resists  the  revolv- 
ing motion  of  the  wheels,  and  if  the  resistance  of  this  friction  is  greater 
than  the  propelling  force,  the  car  will  ultimately  stop ; and  when  the 
weight  of  an  engine  is  supported  on  the  driving-wheels  and  they  rest  on 
the  rails,  the  friction  between  them  and  the  rails,  as  has  already  been 
pointed  out,  resists  their  slipping  on  each  other,  and  thus  enables  a loco- 
motive to  exert  tractive  force.  Friction  also  resists  the  turning  of  an  axle 
on  its  journal,  which  is  overcome  by  the  tractive  power  of  the  locomotive. 

Question  554.  On  what  does  the  amount  of  friction  depend ? 

Answer.  The  amount  of  friction  of  two  bodies  in  contact  depends  (1) 
UPON  THE  PRESSURE  OF  THE  ONE  ON  THE  OTHER,  AND  SO  FAR  AS  THE 
FRICTION  OF  MOST  OF  THE  PARTS  OF  RAILROAD  MACHINERY  IS  CON- 
CERNED MAY  IN  PRACTICE  BE  REGARDED  AS  INDEPENDENT  OF  THE  AREA 
OF  THE  SURFACES  IN  CONTACT;  (2)  ON  THE  NATURE  OF  THE  MATERIALS 
IN  CONTACT  ; (3)  ON  THE  NATURE  OF  THE  SUBSTANCE,  SUCH  AS  OIL  OR 
OTHER  LUBRICANT,  WHICH  IS  INTERPOSED  BETWEEN  THEM;  (4)  ON  THE 
speed;  (5)  ON  the  temperature.  Thus,  a brick  will  slide  down  an  in- 
clined board  as  easily  if  it  is  laid  on  its  broadest  side  as  it  will  if  placed 
edgewise;  and  if  a cast  iron  plate,  say  10  inches  square,  is  planed  and 
scraped,  so  as  to  be  as  nearly  a perfect  plane  surface  as  it  is  possible  to  make 
it,  it  will,  if  loaded  with,  say  a hundred  pounds’  weight,  slide  on  a similar 
true  surface  as  easily  as  another  plate  with  half  as  much  area  and  loaded 


Friction  and  Lubrication. 


441 


with  the  same  weight.  A shaft  resting  against  a long  bearing  will  require 
no  more  power  to  turn  it  than  would  be  needed  if  the  bearing  was  short.* 

Question  555.  What  is  meant  by  the  “ co-efficient  of  friction  ” ? 

Answer.  It  is  the  proportion  which  the  resistance  to  sliding  motion 
bears  to  the  force  pressing  the  surfaces  together.  Thus,  a smooth,  clean, 
and  dry  cast  iron  plate  loaded  with  100  lbs.  will  require  a force  of  about 
15  ibs.  or  fifteen  one-hundredths  of  the  weight  or  pressure  of  the  plates, 
to  slide  them  on  each  other.  The  co-efficient  of  friction  is  therefore  said 
to  be  0.15,  and  with  any  other  weight  or  pressure  on  the  plates  we  could 
determine  the  force  required  to  slide  them  on  each  other  by  multiplying 
the  pressure  by  the  co-efficient  of  friction.  Thus,  if  the  plates  were 
loaded  with  250  lbs.,  the  force  required  to  slide  the  one  on  the  other 
would  be  equal  to  250x0.15=37.5  lbs.  The  co-efficient  of  friction,  how- 
ever, varies  for  different  materials.  Thus,  while  it  is  0.15  between  two 
pieces  of  smooth,  clean,  and  dry  cast  iron,  the  co-efficient  of  a piece  of 
brass  on  cast  iron,  under  similar  conditions,  is  0.22,  and  of  two  pieces 
of  wood  about  0.4. 

Question  556.  What  is  the  effect  of  introducing  some  unguent  or 
lubricating  material such  as  oil,  between  the  surfaces  in  contact  ? 

Answer.  The  co-efficient  of  friction  is  very  much  reduced  thereby. 
Thus  the  co-efficient  of  the  cast  iron  plates,  if  their  surfaces  are  greased 
with  tallow,  is  0.1 ; if  lubricated  with  lard,  0.07,  with  olive  oil,  0.064,  and 
with  lard  and  plumbago,  0.055,  thus  showing  that  the  amount  of  friction 
depends  very  much  upon  the  nature  of  the  lubricant  which  is  used,  as  well 
as  on  that  of  the  material  in  contact. 

QUESTION  557.  What  effect  on  the  amount  of  friction  has  the  manner 
of  applying  the  lubricating  material  to  the  surfaces  in  contact  ? 

Answer.  The  more  perfect  the  lubrication  the  less  will  be  the  co-effi- 
cient of  friction  It  has,  for  example,  been  found  by  experiments  made 
with  cast  iron  shafts  turning  on  bearings  of  the  same  material  that  when 
the  lubricating  material  was  applied  so  that  the  surfaces  were  only 
“ unctuous,”  that  is,  slightly  greasy,  the  co-efficient  of  friction  was  very 
little  less  than  Arhen  they  were  dry,  that  is,  when  there  was  no  lubricating 
substance  between  them,  and  that  when  they  were  greased  “from  time  to 
time”  the  co-efficient  was  reduced  to  0.07  and  0.08 ; but  when  they  were 
continually  oiled  it  averaged  0.05,  and  sometimes  fell  as  low  as  0.025. 
showing  that  with  the  best  lubrication  the  friction  was  only  one-sixth 

* Ordinarily  somewhat  less  power  is  required  to  turn  it  if  the  bearing  is  long  than  if  it  is  short, 
the  reasons  for  which  will  be  explained  hereafter. 


442 


Catechism  of  the  Locomotive. 


what  it  was  when  the  surfaces  were  only  “ unctuous.”  Between  these  two 
limits  there  is  every  degree  of  frictional  resistance,  according  to  the  con- 
dition of  lubrication.  This  shows  how  important  it  is  that  the  oiling  fix- 
tures of  a locomotive  should  be  kept  in  the  most  perfect  condition  and  the 
utmost  care  be  exercised  in  keeping  every  part  of  it  which  is  subjected  to 
friction  thoroughly  lubricated. 

QUESTION  558.  What  effect  does  the  pressure  per  square  inch  of  the 
surfaces  in  contact  have  upon  the  lubrication  ? 

Answer.  The  tendency  is,  when  this  pressure  becomes  excessive,  to 
press  out  the  lubricant  which  is  between  the  two  surfaces,  and  ordinary 
experience  proves  that  the  greater  the  weight  or  the  force  per  square  inch 
with  which  two  bodies  are  pressed  together,  the  greater  is  the  difficulty  of 
keeping  them  perfectly  lubricated. 

Thus,  it  is  easier  to  keep  the  journals  of  a car  well  lubricated  when  it  is 
empty  than  when  it  is  heavily  loaded,  and  the  guide-bars  of  a locomotive 
are  more  liable  to  be  abraded  when  the  engine  is  pulling  a heavy  load 
than  with  a light  one. 

QUESTION  559.  What  effect  has  the  velocity  of  the  surfaces  in  contact 
on  the  friction  and  lubrication  ? 

Answer.  With  the  surfaces  in  the  same  condition,  the  friction  is  nearly 
independent  of  the  velocity  of  the  motion  of  the  surfaces  against  each 
other,  but  perfect  lubrication  becomes  more  difficult  as  the  velocity 
increases,  so  that  an  increase  of  velocity  will  often  increase  indirectly  the 
amount  of  friction.  Thus,  taking  our  previous  illustrations,  it  is  more 
difficult  to  keep  the  journals  of  a car  or  engine  well  lubricated  when  run- 
ning fast  than  when  running  slow,  and  the  same  thing  is  true  of  the  guide- 
bars  and  other  parts. 

QUESTION  560.  What  considerations  should  govern  the  proportions  of 
frictional  bearings  for  locomotives  and  other  machines  ? 

Answer.  The  dimensions  to  be  given  them  should  not  be  determined 
from  a consideration  solely  of  their  resistance  to  rupture,*  but  they  should 
be  made  so  large  that  the  pressure  they  must  bear  will  be  distributed  over 
so  much  surface  that  the  proportion  borne  by  each  square  inch  will  be 
comparatively  small,  thus  making  good  lubrication  much  less  difficult, 
and  consequently  reducing  the  co-efficient  of  friction. 

QUESTION  561.  Is  not  the  amount  of  energy  required  to  overcome  the 
friction  on  a journal  of  large  diameter  greater  than  would  be  required  if 
the  journal  was  smaller ? 


* Morin’s  Mechanics. 


Friction  and  Lubrication. 


443 


Answer.  If  the  co-efficient  of  friction  in  the  two  cases  is  the  same,  un- 
doubtedly the  large  journal  will  require  the  greatest  expenditure  of  energy 
to  turn  it,  because  its  periphery  moves  further  than  that  of  the  small  one ; 
but  the  advantage  attributed  to  large  journals  is  that  they  can  be  lubri- 
cated more  perfectly,  because  their  surfaces  being  larger  the  pressure  is 
not  so  great  per  square  inch,  and  thus  the  gain  from  the  reduction  of  the 
co-efficient  of  friction  is  greater  than  the  loss  attributable  to  the  increase 
of  the  diameter  of  the  journal.  Thus,  if  a car  journal  is  3^  inches  in 
diameter  x 5^  inches  long,  the  available  surface  exposed  to  friction  is 
equal  to  that  of  a longitudinal  section  of  the  journal,  or  3£  x 5-|=17.875 
square  inches.*  Supposing  now  that  the  journal  is  loaded  with  5,000  lbs., 
and  the  average  co-efficient  of  friction  is  0.085.  In  one  revolution  of  the 
wheel  the  journal  will  move  0.85  of  a foot,  and  therefore  5,000  x .085  x .85= 
361J  foot-pounds  of  work.  If,  now,  the  journal  is  made,  as  has  been  pro- 
posed, 3f  x 7 inches,  then  its  effective  surface  will  be  equal  to  26£  square 
inches,  but  the  journal  will  move  0.98  of  a foot  in  one  revolution.  If,  how- 
ever, the  lubrication  is  improved  by  the  increased  area  of  the  journal  so  that 
the  co-efficient  of  friction  is  reduced  from  0.085  to  0.07,  then  the  energy 
consumed  in  one  revolution  will  be  equal  to  5,000  x 0.07  x .98=343  foot- 
pounds, or  less  than  was  consumed  with  the  small  journals.  The  co- 
efficient of  friction  is  assumed,  and  could  only  be  determined  by  experi- 
ment, but  the  assumption  shows  how  the  resistance  of  the  large  journals 
may  be  less  than  that  of  the  small  ones.  Of  course  it  would  be  better  to 
give  the  increased  bearing  surface  by  adding  to  the  length  of  the  journal, 
but  nearly  all  locomotives  and  car  journals  must  be  increased  in  diameter, 
as  well  as  in  length,  when  they  are  enlarged,  in  order  to  have  the  requisite 
strength  to  carry  the  loads  they  must  bear. 

Question  562.  Is  the  law  that  friction  is  in  proportion  to  the 

PRESSURE  ON  EACH  OTHER  AND  INDEPENDENT  OF  THE  AREA  OF  THE 
SURFACES  OF  CONTACT  true  under  all  circumstances  ? 

Answer.  Probably  not.  The  exact  law  of  the  variation  of  friction 
which  is  due  to  change  of  pressure  when  the  surfaces  are  thoroughly 
lubricated,  or  change  of  area  when  they  are  not  lubricated,  and  the  pres- 
sures become  excessive,  is  not  thoroughly  understood.  It  seems  probable, 
at  least,  that  with  surfaces  thoroughly  well  lubricated,  that  friction  is,  to 


* The  reason  for  this  is  that  the  effective  surface  of  the  journal  which  resists  the  pressure  of 
the  bearing,  is  equivalent  only  to  the  horizontal  area  just  as  the  surface  which  resists  the  pres- 
sure inside  of  a boiler  is  equivalent  to  the  diameter  multiplied  by  its  length,  as  was  explained  in 
answer  to  Question  241. 


444 


Catechism  of  the  Locomotive. 


some  extent  at  least,  independent  of  speed  and  pressure,  and  also  that 
with  excessive  pressure — as  of  the  driving-wheels  of  a locomotive  on  the 
rails  without  lubrication — that  the  friction  increases  with  the  area  of  the 
surfaces  in  contact,  and  not  in  proportion  to  the  weight  on  them  alone. 

QUESTION  563.  What  effect  has  the  nature  of  the  materials  in  contact 
on  the  friction  ? 

Answer.  The  amount  of  friction  and  also  the  lubrication  is  very  much 
influenced  by  the  nature  of  the  bearing  surface,  and  also  by  the  material 
used  as  a lubricant.  Some  metals,  such  as  brass  and  other  alloys,  are 
much  less  liable  to  abrasion,  and  seem  to  retain  lubricants  on  their  sur- 
faces better  than  other  metals,  and  are  therefore  much  used  for  journal 
and  other  bearings.  Some  substances,  especially  oils,  are  good  lubricants, 
while  other  materials  of  apparently  similar  nature  are  not.  The  reason 
why  these  materials  possess  these  properties  while  others  are  without  them 
is  not  known,  and  the  value  of  any  material  as  a lubricant,  or  the  degree 
to  which  another  will  resist  friction  without  abrasion,  can  only  be  tested 
by  experiment. 

Question  564.  How  are  the  journals  of  the  axles  of  locomotives  lubri- 
cated? 

Answer.  The  driving  and  engine  truck  axle  boxes  have  oil-holes  and 
receptacles  on  top,  which  are  filled  with  cotton  or  woolen  waste,  into 
which  the  oil  is  poured  when  the  engine  is  standing  still.  The  tender 
axle  boxes  have  receptacles  below  the  journals,  which  are  filled  with  waste 
and  saturated  with  oil,  as  explained  in  answer  to  Question  599. 

QUESTION  565.  How  are  the  crank-pins  and  cross-head  guides  lubri- 
cated? 

Answer.  The  guides  and  the  connecting-rods  have  oil  or  lubricating 
cups  attached  to  them  above  the  bearings.  Such  cups  are  shown  in  Plate 
III,  on  top  of  the  guide-bars,  62,  and  above  the  crank-pins,  5 5.  Fig.  375 
is  an  outside  and  fig.  376  a sectional  view  of  an  oil-cup  for  locomotive 
guides.*  It  consists  of  an  internal  glass-cup,  a a , which  is  enclosed  in  a 
brass  case,  b,  which  has  round  openings  on  its  four  sides,  shown  at  a , fig. 
375,  so  that  it  can  be  seen  how  much  oil  the  cup  contains.  The  glass  cup 
is  held  in  place  by  a cap,  c,  which  is  screwed  on  the  case,  b.  India-rubber 
washers  are  placed  above  and  below  the  glass  cup,  to  make  tight  joints 
when  the  cap  is  screwed  down.  The  oil  is  poured  into  the  cavity,  d,  in 
the  cap,  c,  and  runs  down  into  the  glass  cup,  a,  through  openings  not 
shown  in  the  engraving.  From  a it  flows  to  the  bearings  through  the 


* Manufactured  by  the  Nathan  Manufacturing  Company  of  New  York. 


Friction  and  Lubrication. 


445 


opening,  e.  The  rate  of  flow  is  regulated  by  a conical  screw-plug,  f,  which 
can  be  adjusted  so  as  to  increase  or  diminish  the  flow  of  oil  to  the  bear- 
ings. The  lower  part,  gy  of  the  cup  is  screwed  into  the  guide-bars.  The 


Fig.  375.  Fig.  376. 

Oil-Cup  for  Locomotive  Guide-Bars. 


cap,  c , has  a loose  cover,  h , to  exclude  dirt  from  the  cup.  It  is  held  by  a 
chain,  t\  to  prevent  its  being  lost. 

Fig.  377  is  an  external  view  of  a similar  oil-cup  for  connecting-rods. 


Fig.  377.  Oil-Cup  for  Connecting-Rods. 

The  cap  is  screwed  on  the  case,  and  the  flow  of  oil  is  adjusted  by  a small 
rod  or  pin,  the  lower  end  of  which  rests  on  the  surface  of  the  crank-pin. 


446 


Catechism  o ^ the  Locomotive. 


There  is  a great  variety  of  oil-cups  in  use,  and  much  ingenuity  has  been 
exercised  in  devising  appliances  to  regulate  the  supply  of  oil. 

QUESTION  566.  How  are  the  slide-valves  and  pistons  of  a locomotive 
lubricated? 

Atiswer.  The  method  which  was  formerly  employed  was  to  attach  an 
oil-cup  to  the  top  of  the  steam-chest,  by  which  oil  was  supplied  to  the 
valve  below  when  the  steam  was  shut  off.  To  do  this  the  fireman  had  to 


go  to  the  front  end  of  the  engine.  To  avoid  this  pipes  were  connected  to 
the  steam-chests,  and  extended  back  to  the  cab  with  oil-cups  in  the  cab, 
so  that  the  valves  could  be  oiled  from  the  cab  without  going  out  to  the 
front  of  the  engine.  Of  late  years  what  are  called  “ sight-feed  lubricators 


Friction  and  Lubrication. 


447 


which  supply  oil  continuously  to  the  cylinders,  are  used.  These  ^.re  placed 
in  the  cab,  and  are  connected  to  the  steam-chests  by  pipes.  Fig.  378 
represents  an  end  view,  fig.  379  a sectional  view  on  a plane  parallel  to  that 
of  fig.  378,*  and  fig.  379  a side  view  of  such  a lubricator.  In  this  class  of 
lubricators  the  weight  of  a column  of  water  displaces  the  oil  in  the  cup, 
and  causes  it  to  flow  upward , drop  by  drop,  through  water  in  glass-tubes 
to  the  pipes,  which  are  connected  to  the  steam-chests. 


Fig.  379.  Sight-Feed  Lubricator. 


In  fig.  379,  / is  the  reservoir  for  holding  the  oil,  which  is  filled  through 
the  plug,  A,  figs.  378  and  380.  Ads  a condenser,  to  which  steam  is  conducted 
by  a pipe  on  top  connected  to  the  boiler,  as  shown  in  fig.  380.  As  the  steam 
is  condensed  in  E,  fig.  379,  the  water  of  condensation  flows  down  into  the 

* Manufactured  by  the  Nathan  Manufacturing  Company,  of  92  Liberty  Street,  New  York. 


448 


Catechism  of  the  Locomotive. 


reservoir,  /,  by  a pipe  not  shown  in  the  engraving,  and  the  water  being 
heavier  than  the  oil,  the  former  sinks  to  the  bottom  of  /,  and  the  oil 
floats  on  top.  If  the  reservoir  is  half  full  of  water,  and  is  then  entirely 
filled  with  oil,  the  water  as  it  condenses  in  E will  flow  down  to  the  bottom 
of  /,  and  cause  the  oil  to  flow  slowly  into  the  top  of  the  pipe,  P,  and  from 


Fig.  380.  Sight-Feed  Lubricator. 


there  down  into  the  channel,  J,  below  /,  and  thence  to  the  glass  tubes,  K 
K , which  are  filled  with  water  by  the  condensation  of  steam.  This  flows 
into  them  through  the  pipes,  L.  The  oil  then  passes  upward,  drop  by 
drop,  through  the  water  in  the  tubes,  K K,  as  shown  on  the  left-hand  side 
of  fig.  379,  and  it  then  passes  by  an  opening  above  the  tubes  to  the  pipes. 


Friction  and  Lubrication. 


449 


H,  one  of  which  is  shown  in  fig.  380,  and  through  them  to  the  steam- 
chests.  The  flow  of  oil  is  thus  constantly  in  sight,  and  it  can,  therefore, 
be  known  whether  the  lubrication  is  continuous  and  regular.  The  pipes, 
Z,  inside  of  the  reservoir  conduct  a small  quantity  of  steam  and  water  to 
the  pipes,  H , after  the  glass  tubes,  K K,  are  filled,  and  in  this  way  the  oil, 
when  it  reaches  the  surface  of  the  water  in  the  tubes,  K K,  mingles  with 
the  current  of  steam,  which  thus  forms  a steam  lubricant  that  is  said  to 
reach  and  oils  all  parts  of  the  valves  and  cylinders. 

The  quantity  of  oil  entering  the  sight-feed  glasses,  K K,  can  be  regu- 
lated by  the  valves,  C C. 

The  two  sides  of  the  lubricator  form  two  distinct  and  entirely  separate 
oilers,  which  work  independently  for  each  cylinder.  The  feed  is  regular 
and  continuous,  whether  steaming  or  with  steam  shut  off,  going  up  or 
down  grade. 

Each  side  is  provided  with  an  independent  “ hand  ” or  auxiliary  oiler, 
O O,  to  be  used  in  case  any  of  the  glass  tubes  should  break.  The  auxiliary 
oilers  communicate  directly  with  the  pipes,  H,  and  can  be  used  as  simple 
oilers  in  case  of  need.  In  case  one  of  the  glass  tubes  should  be  broken, 
the  valve,  F,  above  it  should  be  closed,  which  will  prevent  the  escape  of 
steam  from  the  broken  tube. 

Another  glass  tube,  G , forms  a gauge  to  show  the  quantity  of  oil  and 
water  in  the  reservoir,  /,  and  a cock,  W,  is  used  to  drain  the  reservoir,  /, 
before  refilling  it. 

The  valve,  D , opens  or  closes  the  opening  which  communicates  from 
the  condenser,  E,  to  the  reservoir,  Z This  valve  should  be  closed  when 
the  engine  has  completed  its  run.  If  it,  the  valves,  C C,  and  the  steam- 
valve,  B , are  left  open,  oil  will  continue  to  feed  into  the  cylinders  so  long 
as  there  is  any  steam  in  the  boiler. 

The  following  directions  have  been  given  by  the  manufacturers  for  the 
care  of  the  sight-feed  lubricators  : 

Directions  for  Using  the  Nathan  Sight-Feed  Lubricator. 

“ Fill  the  cup  with  clean,  strained  oil,  through  the  filling  plug.  A,  then 
open  the  water- valve,  D. 

“To  start:  Open  the  steam-valve,  B,  wait  until  the  sight-feed  glasses 
have  filled  with  condensed  water,  then  regulate  the  feed  by  the  valves,  C 
C.  To  stop : Close  the  valves,  C C. 

“To  renew  the  supply  of  oil : Close  the  valves,  C and  D,  and  draw  off 


450 


Catechism  of  the  Locomotive. 


the  water  at  the  waste-cock,  E ; then  fill  the  cup  and  start  again  as  before, 
always  opening  the  valve,  D,  first. 

“ The  valves,  F F,  must  be  always  kept  open,  except  when  one  of  the 
glasses  breaks.  In  such  case  close  the  valves,  F D and  B,  to  shut  off 
the  cup,  and  use  the  auxiliary  oilers,  O O,  as  common  cab  oilers. 

“ The  valve,  D,  must  be  closed  or  opened  in  advance  of  the  valve,  B, 
whenever  this  latter  is  closed  or  opened. 

“ Once  in  two  weeks,  at  least,  blow  out  the  cup  with  steam,  opening  the 
valves  wide,  with  the  exception  of  the  filling  plug,  A,  which  should  remain 
closed.” 


CHAPTER  XXIII. 


SCREW-THREADS,  BOLTS  AND  NUTS. 

Question  567.  How  must  the  screws  of  bolts  and  nuts  be  made , in  order 
to  fit  each  other  ? 

Answer.  Each  size  of  screw  must  be  made  of  exactly  the  same  diam- 
eter, and  the  threads  must  be  of  the  same  form  and  proportions  and  pitch. 

Question  568.  What  is  meant  by  the  “ pitch  ” of  a thread? 

Answer.  It  is  the  distance  the  thread  progresses  lengthwise  of  the 
screw  in  one  revolution.  Thus,  if  a single-threaded  screw  has  ■§■  of  an 
inch  pitch,  it  means  that  the  threads  are  £ of  an  inch  apart,  measured  from 
the  centre  of  one  thread  to  the  centre  of  that  next  to  it,  and  therefore  there 
are  eight  threads  to  each  inch  in  length  of  the  screw. 

Question  569.  What  is  meant  by  a “ single-threaded"  screw? 


Fig.  381.  Full  Size.  Fig.  382.  Eight  Times  Full  Size. 

Sections  of  Screw-Threads. 

Answer.  It  means  a screw  with  but  one  thread  instead  of  two  or  more. 
Thus,  if  we  take  a string  and  wind  it  around  a pencil,  it  will  represent  a 
single-threaded  screw,  and  if  we  take  two  or  three  strings  and  wind  them 
parallel  to  each  other,  they  will  represent  double  or  treble-threaded 
screws.  The  latter  kinds  are  seldom  or  never  used  on  locomotives,  so 
that  in  the  following  discussion  only  single-threaded  screws  will  be  re- 
ferred to. 

Question  570.  What  is  the  usual  form  of  the  threads  of  screws? 


452 


Catechism  of  the  Locomotive. 


Answer.  Until  a few  years  ago  the  most  common  form  was  what  is 
called  the  V-thread,  represented  in  fig.  381  (and  on  an  exaggerated  scale 
in  fig.  882),  which  was  made  sharp  at  both  the  top  and  bottom.  It  is  ev! 
dent  that  if  such  a thread  for  one  screw  is  made  very  pointed,  and  that 
for  another  is  blunt,  that  the  nut  for  the  one  will  not  fit  the  other  accu- 
rately, and  also  that  if  a nut  has  eight  threads  to  the  inch,  it  will  not  fit 
on  a bolt  with  nine.  Owing  to  the  fact  that,  for  a long  time,  no  common 
standard  had  been  agreed  upon  for  the  form,  proportions  or  pitch  of 
screws,  there  was  a very  great  diversity  in  these  respects  in  the  screws 
which  have  been  used  in  the  construction  of  locomotives  and  other 
machinery.  In  1864  the  inconvenience  and  confusion  from  this  cause 
became  so  great  that  it  attracted  the  attention  of  the  Franklin  Institute, 
of  Philadelphia,  and  a committee  was  appointed  by  that  association  to 
investigate  and  report  on  the  subject.  That  committee  recommended 
the  adoption  of  the  Sellers  system  of  screw-threads  and  bolts,  which  was 
devised  by  Mr.  William  Sellers,  of  Philadelphia.  This  same  system  was 
subsequently  adopted  as  the  standard  by  both  the  Army  and  Navy  De- 
partments of  the  United  States,  and  then  by  the  Master  Mechanics’  and 
Master  Car  Builders’  Associations,  so  that  it  may  now  be  regarded,  and  in 
fact  is  called,  the  United  States  standard,  but  the  design  is  due  to  Mr. 
Sellers,  and  the  system  should  be  designated  by  his  name. 

QUESTION  571.  In  establishing  a standard  system  of  screws  and  threads , 
what  is  the  first  thing  which  must  be  determined? 


Fig.  383.  Full  Size. 


Fig.  384.  Eight  Times  Full  Size. 


Sections  of  Sellers’  Screw-Threads. 


Answer.  The  number  of  threads  to  the  inch,  or  the  pitch  of  the  threads 
for  screws  of  different  diameters. 


Screw-Threads,  Bolts  and  Nuts. 


453 


Question  572.  What  is  the  standard for  the  nutnber  of  threads  to  the 
inch  for  the  different  sized  screws  of  the  Sellers  system  ? 

Answer.  The  number  of  threads  with  their  other  proportion  is  given 
in  the  table  on  page  454. 

QUESTION  573.  What  is  the  form  of  the  thread  of  this  standard ? 

Answer.  The  form  is  shown  in  fig.  383,  and  on  an  exaggerated  scale  by- 
fig.  384.  It  is  similar  to  the  V-thread,  excepting  that  it  is  flattened  at  the 
top  and  bottom. 

Question  574.  What  advantages  has  the  Sellers form  of  screw-threads 
enter  the  old  V-form  ? 

Answer.  The  flattened  point  or  edge  makes  the  thread  less  liable  to 
injury  by  being  battered,  and  the  diameter — and  consequently  the  strength 
— of  a screw  with  the  Sellers  thread  at  n , fig.  384,  at  the  root  of  the  thread, 
is  considerably  greater  than  a thread  of  the  V-form. 

QUESTION  575.  What  other  reasons  are  there  for  the  adoption  of  this 
form  of  thread? 

Answer.  It  has  already  been  pointed  out  that  if  a screw  is  made  with 
a “ blunt  ” thread  it  will  not  fit  a nut  with  very  acute  or  “ sharp  ” thread  ; 
or,  if  the  thread  of  the  bolt  is  acute  and  that  in  the  nut  obtuse,  they  will 
fit  imperfectly.  It  is,  therefore,  necessary  in  a standard  system  to  fix  upon 
the  angle  which  the  sides  of  the  thread  shall  bear  to  each  other.  In  the 
Sellers  standard  system  this  angle  was  made  60  degrees,  because  that  is 
easily  laid  off  without  special  instruments,*  and  is,  perhaps,  as  good  as  or 
better  than  any  other  form  for  the  threads. 

It  is  obvious  that  if  a tool  is  ground  with  its  sides  at  an  angle  of  60 
degrees  to  each  other,  if  the  point  is  made  sharp,  after  a very  little  use  it 
will  be  worn  more  or  less  so  that  the  bottom  of  the  thread  will  not  be  cut 
perfectly  sharp,  and  therefore  it  will  be  difficult  to  make  bolts  and  nuts 
with  threads  of  this  form  to  fit  each  other  accurately. 

It  will  also  be  impossible  to  measure  the  diameter  of  the  screw  at  the 
bottom  of  the  thread  if  it  is  made  sharp,  as  its  depth  will  vary  as  the  point 
of  the  tool  wears,  and  it  is  almost  impossible  to  measure  the  diameter  of 
such  a screw  precisely  with  ordinary  calipers.  To  obviate  these  evils  the 
standard  threads  are  made  flat  on  the  top,  and  it  is  evident — as  has  been 
pointed  out — that  a similar  shape  at  the  bottom  will  give  increased 
strength  to  the  bolt  as  well  as  conform  to  and  fit  the  thread  in  the  nut. 

* This  can  be  done  by  drawing  a circle  of  any  diameter,  and  subdividing  the  circumference 
into  six  equal  parts  with  the  radius.  Lines  drawn  from  the  points  of  division  to  the  centre  will 
have  an  inclination  of  60  degrees  to  each  other. 


Screw-Threads,  Bolts  and  Nuts. 


455 


To  give  this  form  requires  only  that  the  point  of  the  cutting  tool 
shall  be  taken  off,  and  it  is  evident  that  then  this  form  of  thread  can 
be  cut  in  a lathe  with  the  same  tool  and  in  the  same  manner  as  the  sharp 
thread. 

The  advantage  of  the  Sellers  form  of  thread,  in  the  matter  of  strength, 
will  be  apparent  if  the  form  of  a V thread  of  the  same  diameter  as  the 
Sellers  thread  is  laid  off,  in  fig.  384,  as  shown  by  the  dotted  lines,  b c e d. 
It  is  plain  from  this  that  the  small  triangular  portion  of  the  top  of  the  V 
thread,  between  the  two  horizontal  dotted  lines,  at  1 and  2,  has  less 
strength  than  the  corresponding  part  of  the  Sellers  thread  between  these 
lines ; and  it  is  also  plain  that  if  the  sides,  c e and  e d of  the  V thread  are 
made  of  the  same  angle  as  the  Sellers  thread,  that  the  former  must  be  cut 
deeper  than  the  latter  by  a distance  equal  to  a e , and  that  the  bolt  will 
be  weakened  in  proportion  to  the  amount  of  metal  thus  cut  away  at  the 
root  of  the  thread. 

Question  576.  What  are  the  proportions  of  the  standard  threads? 

Answer.  The  rule  given  by  Mr.  Sellers  for  proportioning  the  thread  is 
as  follows:  “Divide  the  pitch,  or,  what  is  the  same  thing,  the 

SIDE  OF  THE  THREAD  ( C 3,  fig.  384),  INTO  EIGHT  EQUAL  PARTS;  TAKE  OFF 
ONE  PART  (e)  FROM  THE  TOP  AND  FILL  IN  ONE  PART  (3)  IN  THE  BOTTOM 
OF  THE  THREAD : THEN  THE  FLAT  TOP  (below  C ) AND  BOTTOM  (below  a) 
WILL  EQUAL  ONE-EIGHTH  OF  THE  PITCH,  THE  WEARING  SURFACE  (V)  WILL 
BE  THREE-QUARTERS  OF  THE  PITCH,  AND  THE  DIAMETER  OF  SCREW  ( n , fig. 
383)  AT  BOTTOM  OF  THE  THREAD  WILL  BE  GIVEN  IF  WE  DIVIDE  1.002  BY 
THE  NUMBER  OF  THREADS  PER  INCH  AND  DEDUCT  THE  QUOTIENT  FROM 
THE  OUTSIDE  DIAMETER  ( d fig.  383)  OF  THE  SCREW." 

The  form  and  proportions  of  the  thread  are  shown  in  fig.  384,  which  has 
been  drawn  eight  times  the  size  of  a thread  for  a bolt  one  inch  in  diam- 
eter, so  as  to  represent  the  different  parts  clearly ; x represents  the  pitch, 
and  D the  depth  of  the  thread  ; d,  fig.  383,  represents  the  outside  diameter 
of  the  screw,  and  n the  diameter  at  the  bottom  or  root  of  the  thread. 
The  width  of  the  flat  part  of  the  thread  at  the  top  and  bottom  of  the 
threads  is  shown  at  c,  d , and  a , fig.  384,  and  s indicates  the  length  of  the 
side  or  wearing  surface  of  the  thread. 

For  practical  use  in  the  shop  a gauge  like  that  shown  in  fig.  385  will  be 
found  convenient  for  grinding  the  tools  to  the  proper  form  for  making  the 
standard  screws.  With  this  gauge  the  screw  cutting-tool  can  first  be 
ground  to  the  proper  angle  by  fitting  it  to  the  deepest  notch,  and  the 
requisite  quantity  should  then  be  taken  off  the  point  by  fitting  it  to  the 


456 


Catechism  of  the  Locomotive. 


notch  representing  the  form  of  thread  for  the  sized  bolt  or  number  of 
threads  to  the  inch  which  it  is  intended  to  cut. 

Question  577.  What  other  precaution  must  be  taken  to  secure  inter- 
changeability of  screw  bolts  and  nuts  ? 

Answer.  Great  care  must  be  taken  that  the  diameters  of  the  screws  are 
accurately  maintained  to  the  standard  sizes.  The  diameters  of  the  stand- 
ard sizes  of  screws  are  given  in  the  table  on  page  454.  It  has  been  a 
common  practice  to  make  screws  somewhat  larger  than  these  sizes 
because  iron  is  often  rolled  larger  in  diameter  than  its  nominal  size,  and 
then  the  superfluous  metal  must  be  cut  away  to  reduce  the  screw  to  the 


standard  size.  It  should  be  distinctly  known  that  there  are  no  standard 
screws  for  bolts  and  nuts  which  are  a small  fraction  of  an  inch  larger  or 
smaller  than  the  diameters  given  in  the  table,  and  that  a screw  slightly 
larger  or  smaller  in  diameter  than  the  sizes  given  does  not  conform  to 
the  standard. 

Whenever  this  standard  for  threads  is  used,  if  any  pretense  at  all  is 
made  to  accuracy  of  workmanship,  careful  attention  should  be  given  to 
the  form  and  proportion  of  the  threads  as  well  as  to  the  number  to  the 
inch. 

It  is  impossible,  however,  with  the  ordinary  tools  and  appliances  in  use 


Screw-Threads,  Bolts  and  Nuts. 


457 


in  machine  shops,  to  make  taps  and  dies  with  sufficient  amount  of  pre- 
cision, so  that  the  bolts  and  nuts  cut  with  them  will  always  be  interchange- 
able. Such  tools  are  now  made  in  establishments  provided  with  special 
machinery,  appliances,  and  workmen  required  to  secure  and  maintain 
exact  uniformity  and  the  necessary  degree  of  precision  to  insure  inter- 
changeability. 

QUESTION  578.  What  has  been  done  to  secure  uniformity  in  the  diame- 
ters of  screws? 

Answer.  The  Master  Mechanics’  and  Master  Car  Builders’  Associations 
have  adopted  limits  for  the  diameters  of  round  bar  iron.  It  has  been 
specified  by  these  Associations  that  such  iron  shall  not  vary  from  its  nom- 
inal size  more  than  the  amount  given  in  the  following  table : 

LIMITS  OF  SIZE  OF  ROUND  ROLLED  IRON. 


Nominal  Diameter  of  Iron. 

Inches. 

Maximum 
or  + Size. 
Inches. 

Minimum 
or  — Size. 
Inches. 

Total 

Variation. 

Inches. 

>4 

.2550 

.2450 

.010 

.3180 

.3070 

.011 

.3810 

.3690 

.012 

.4440 

.4310 

.013 

14 

.5070 

.4930 

.014 

.5700 

.5550 

.015 

% 

.6330 

.6170 

.016 

94 

.7585 

.7415 

.017 

% 

.8840 

.8660 

.018 

1.0095 

.9905 

.Old 

114 

1.1350 

1.1150 

.020 

114 j 

1.2605 

1.2395 

.021 

Caliper  limit  gauges,  like  that  shown  in  fig.  386,  are  made  by  the  Pratt- 
Whitney  Company,  of  Hartford,  Conn.,  for  measuring  bar  iron.  The  two 
ends  of  the  gauges  are  made  of  the  maximum  and  minimum  dimensions 
given  in  the  table,  and  the  Associations  already  referred  to  have  recom- 
mended that  round  iron  of  the  nominal  standard  sizes  be  made  of  such 
diameter  that  each  size  will  enter  the  large  or  + end  of  the  gauge 
intended  for  it,  in  any  way , and  will  not  enter  the  small  or  — end  in  any 


458 


Catechism  of  the  Locomotive. 


way.  Fig.  387  is  a reference  gauge  which  is  used  for  testing  the  caliper 
gauges  shown  in  fig.  386. 

In  buying  taps  and  dies  the  purchaser  should  see  that  they  conform  in 
every  respect  to  the  standard,  and  in  making  specifications  for  new  work 
similar  care  should  be  exercised  to  secure  the  true  standard,  form  and 
proportion  of  screws.  In  many  shops  the  workman  who  have  the  care  of 


Fig.  387.  Reference  Gauges  for  Round  Iron. 


those  tools  are  entirely  ignorant  of  the  peculiarities  of  the  Sellers  system, 
and  have  only  the  vague  idea  that  so  long  as  they  get  the  proper  number 
of  threads  to  the  inch  they  are  doing  all  that  is  necessary  to  secure  uni- 
formity. Unless,  therefore,  some  care  is  exercised  to  insure  accuracy  of 
workmanship  in  this  department,  the  adoption  of  a “ standard  ” for  screws 
will  not  insure  the  advantages  which  would  result  from  uniformity  of 
screws  and  threads. 

Question  579.  What  is  the  usual  shape  of  nuts? 

Answer.  The  most  common  shape  is  square  or  hexagonal,  as  shown  in 
figs.  388-391,  but  they  are  sometimes  made  cylindrical,  as  shown  in  figs. 
392  and  393,  with  grooves  cut  on  the  outside  to  hold  a wrench. 

Question  580.  Why  is  it  often  essential  to  adopt  some  means  to  pre- 
vent nuts  from  turning  or  unscrewing  ? 

Answer.  When  bolts  and  nuts  are  exposed  to  vibration,  it  is  found  that 
a slackening  is  very  liable  to  occur,  so  that  the  excessive  vibration  on 
locomotives  requires  that  many  of  the  nuts  should  be  locked  in  some 
way. 


Screw-Threads,  Bolts  and  Nuts. 


459 


Question  581.  How  are  nuts  prevented  from  turning  ? 

Answer.  The  simplest  plan,  and  the  one  which  is  most  frequently  em- 
ployed, is  that  shown  in  figs.  394  and  395,  which  is  simply  a second  or 
“ lock  nut  ” screwed  on  over  the  first  and  tightened  down  upon  it.  Lock 
nuts  are  usually  made  thinner  than  the  main  nut,  and  when  that  is  the 
case,  it  is  argued  that  the  thinnest  nut  should  be  screwed  on  the  bolt  first. 


Fig.  394. 


because  if  the  second  nut  is  screwed  down  hard  on  the  first  one,  the 
strain  on  the  bolt  is  borne  by  the  one  last  screwed  on. 

When  lock  nuts  are  used,  if  the  total  thickness  of  the  two  nuts  is  equal 
to  about  one-half  more  than  the  ordinary  proportion  for  the  thickness  of 
nuts,  it  will  be  found  that  sufficient  has  been  done  to  insure  a perfect 
locking. 

When  the  object  is  merely  to  prevent  nuts  from  unscrewing  and  being 
lost,  what  are  called  split  keys  or  cotters  are  used.  These  are  sometimes 
round,  tapered  pins,  shown  in  figs.  388  and  389,  which  are  divided  or  split 
so  that  the  two  parts  can  be  bent  into  the  form  shown  in  fig.  389.  In 
other  cases  they  are  made  of  flat  pieces  of  metal,  as  shown  in  figs.  390  and 
391,  which  are  bent  as  shown  in  fig.  391. 

Question  582.  What  are  the  shapes  of  bolt-heads  ? 

Answer.  They  are  made  in  a variety  of  forms  according  to  their  use, 
but  usually  they  are  either  square  or  hexagonal,  the  same  as  nuts. 

Question  583.  In  what  other  forms  are  bolt-heads  made? 

Answer.  Fig.  396  represents  a bolt  with  a hemispherical  head,  and  fig.. 
397  one  with  a countersunk  head.  The  latter  form  is  used  when  a pro- 
jecting head  would  be  in  the  way  of  something  else.  To  prevent  the  bolt 


460 


Catechism  of  the  Locomotive. 


from  turning  when  a hemispherical  or  countersunk  head  is  used,  a hole  is 
sometimes  drilled  into  the  side  of  the  bolt  and  a pin,  a , fig.  397,  is  fitted 
into  it.  This  pin  rests  in  a corresponding  cavity  cut  in  the  side  of  the 
hole  in  which  the  bolt  fits. 

Fig.  398  represents  a hook-headed  bolt,  which  is  sometimes  used  to 
fasten  tires  on  wheel  centres.  Fig.  399  is  the  form  of  bolt-head  used  to 
move  the  wedges  which  form  the  wearing  surface  for  driving-axle  boxes. 

Question  584.  Are  there  any  standard  sizes  for  bolt-heads  and  nuts? 


Fig.  396.  Fig.  397.  Fig.  398.  Fig.  399. 


Different  Forms  of  Bolt-Heads.  Scale  *4  in.— 1 in. 


Answer.  Yes;  proportions  were  devised  by  Mr.  Sellers  and  were 
adopted  by  the  associations  already  referred  to.  These  are  given  in  the 
table  on  page  454. 

Question  585.  What  is  a washer  ? 

Answer.  A washer,  shown  at  w w,  fig.  388  and  in  fig.  389,  is  a ring  of 
metal  or  other  material,  which  is  put  under  a bolt-head  or  nut  to  give  it  a 
fair  bearing.  Washers  are  also  put  between  bolt-heads  or  nuts  when  they 
bear  on  wood  or  other  yielding  material  to  increase  the  area  of  their  bear- 
ing. 

Question  586.  What  is  a stud? 

Answer.  A stud  is  a bolt  with  a nut  in  place  of  a head.  Studs  are 
screwed  into  their  place  and  are  provided  with  nuts  instead  of  heads,  so 
that  the  stud  need  not  be  unscrewed  to  loosen  or  remove  the  parts  which 
it  secures  or  fastens.  Studs  are  generally  used  to  make  attachments  to 
cast  iron,  such  as  the  cylinder-heads  and  steam  chests  of  locomotives, 
because  a thread  cut  in  cast  iron  is  liable  to  be  injured  by  often  screwing 
and  unscrewing  a bolt  into  and  from  it. 


r.  Scale  % in.=l  ft. 


Fig.  402.  Longitudinal  Section  of  Tender.  Scale  % in. =1  ft. 


wK®5’»'S^»s 


CHAPTER  XXIV. 


TENDERS. 

Question  587.  What  are  locomotive  tenders  for? 

Answer.  They  carry  a supply  of  fuel  and  water  for  locomotives  while 
they  are  running. 

Question  588.  How  are  they  constructed? 

Answer.  The  construction  of  a locomotive  tender  is  shown  by  figs.  400 
to  404.  Fig.  400  is  a side  view,  fig.  401  a plan,  fig.  402  a longitudinal  sec- 
tion, fig.  408  an  inverted  plan,  and  fig.  404  a front  view  with  the  forward 
truck  omitted.  The  tender  has  a rectangular  frame,  A A A A,  made  of 
either  iron  or  wood.  The  frame  shown  in  the  engravings  is  made  of  iron 
channel  bars,  which  are  rolled  bars  whose  section  is  somewhat  similar  in 
form  to  a letter  E with  the  middle  member  omitted.  Tender  frames 
are,  however,  often  made  of  wooden  timbers.  The  frame  is  mounted 
on  a pair  of  trucks,  B B,  figs.  400  and  402.  The  top  of  the  frame 
is  covered  with  planks,  C C C,  which  form  the  floor  of  the  tender. 
On  top  of  this  floor  a sheet  iron  tank,  D D , is  placed,  which 
carries  the  supply  of  water.  This  tank  is  made  somewhat  in  the  form  of 
a letter  3,  as  shown  in  the  plan.  It  is  made  in  this  way  so  that  the  space, 
B' , fig.  401,  between  the  two  branches,  D D,  or  “ legs,”  as  they  are  called, 
will  give  room  for  fuel.  Around  the  upper  edge  of  the  tank  a sheet  iron 
rim,  E E,  is  riveted,  so  as  to  prevent  the  fuel  from  falling  off  when  it  is 
filled  up  above  the  top  of  the  tank. 

Question  589.  How  are  tender  tanks  filled  with  water  ? 

Answer.  They  are  usually  filled  at  water  stations  with  leather  or  canvas 
hose  connected  to  a pipe  or  tank  which  furnishes  a supply  of  water.  The 
appliances  for  doing  this  are  described  in  Chapter  XXV.  The  tank  has 
an  opening,  E,  on  top  called  a “ man-hole  ” or  “ filling  funnel  ” into  which 
the  hose  is  inserted,  and  a stream  of  water  is  then  allowed  to  flow  through 
the  hose  into  the  tank  of  the  tender.  The  tank  which  supplies  water  to 
the  tender  is  located  higher  than  the  tender,  and  the  water  is  usually 
pumped  into  this  tank  so  that  it  will  run  into  the  tender. 

Question  590.  What  other  way  is  there  of  filling  tenders  with  water? 


462 


Catechism  of  the  Locomotive. 


Answer.  To  avoid  frequent  stops  for  water,  express  passenger  locomo- 
tives are  sometimes  provided  with  what  is  called  a “ water-scoop  ” for 
taking  water  while  the  engine  is  running.  This  consists  of  a bent  tube, 
G G G,  figs.  400  to  404,  which  is  attached  to  the  under  side  of  the  tank, 
and  extends  up  inside  of  it  to  the  top.  A long  trough,  H H H,  figs.  402 
and  404,  is  laid  between  the  rails  and  filled  with  water.  The  lower  end  of 


the  bent  tube  or  scoop  has  a joint  or  hinge  at  /,  so  that  it  can  be  lowered 
into  the  trough,  and  the  lower  end,  J,  of  the  scoop  will  then  dip  a few 
inches  into  the  water.  The  motion  of  the  engine  forces  the  water  up  the 
tube,  G G G G,  and  it  is  discharged  into  the  tank  at  K , fig.  402. 


Tenders. 


463 


QUESTION  591.  How  is  the  end  of  the  scoop  lowered  into  the  water  ? 

Answer.  A shaft,  L,  with  two  arms,  M and  N,  is  located  above  the 
lower  end  of  the  scoop.  One  of  these  arms,  N,  is  connected  by  a link,  0, 
to  the  movable  part  of  the  scoop,  and  the  other  arm,  M,  is  connected  by 
a rod,  M P (shown  by  dotted  lines  in  fig.  402),  to  a lever,  P Q R.  The 
fulcrum  of  this  lever  is  at  Q,  and  it  has  a handle,  P,  at  the  top.  By  mov- 
ing the  upper  end  of  the  lever  backward  the  scoop  is  lowered,  and  by 
moving  it  forward  the  scoop  is  raised. 

Question  592.  How  is  the  water  conducted  from  the  te?ider  to  the 
engine  ? 

Answer.  To  each  side  of  the  front  end  of  the  tank,  a piece  of  rubber 
hose,  S,  is  attached,  which  is  connected  at  the  other  end  to  the  pipe  on 
the  engine  which  supplies  the  pump  or  injector  with  water.  In  some 
cases  this  hose  is  connected  directly  to  the  tender  tank,  but  in  others  small 
cast  iron  cisterns,  T T,  are  attached  to  the  bottom  of  the  tank,  and  the 
hose  is  counected  to  them.  A cistern  of  this  kind  is  shown  on  a larger 
scale  in  figs.  406  and  407.  The  purpose  of  these  cisterns  is  to  prevent  air 
being  drawn  into  the  hose  when  the  tank  -is  nearly  empty,  which  would 
interfere  with  the  working  of  the  pumps  or  injectors. 

QUESTION  593.  How  is  com?nunication  opened  and  closed  between  the 
hose  and  the  tank  so  as  to  “ turn  on  ” and  “ shut  off”  water  from  the  hose  ? 

Answer.  This  is  done  by  valves,  U U,  fig.  402  in  the  bottom  of  the 
tank.  A section  of  one  of  these  valves,  with  the  appliances  for  opening 
and  closing  it,  and  the  cistern,  already  referred  to,  is  shown  on  an  enlarged 
scale  by  figs.  405,  406  and  407.  C is  the  cistern  and  V the  valve,  which  is 
operated  by  means  of  a rod,  R R.  This  rod  has  a screw  on  its  upper  end, 
which  is  screwed  into  a casting,  A,  that  is  riveted  to  the  top  of  the  tank. 
The  screw  is  turned  by  a crank  and  handle,  H,  on  its  upper  end.  When 
it  is  turned  in  one  direction  the  valve  is  raised,  and  if  turned  the  opposite 
way  it  is  lowered.  The  wheel,  W,  is  also  screwed  on  the  rod,  R,  and  acts 
as  a check  or  lock  nut  to  hold  the  rod  and  valve  in  any  desired  position. 
The  valve  is  covered  with  a hood  or  strainer,  B,  perforated  with  small  holes, 
which  is  intended  to  prevent  dirt  from  entering  the  hose  and  thus  getting 
into  and  obstructing  the  pump  or  injector.  The  hose  is  connected  to  the 
cistern  and  to  the  supply  pipe  by  a screw-coupling,  D,  similar  to  that  used 
with  ordinary  fire-engine  hose. 

Question  594.  How  are  the  flat  sides  of  the  tank  strengthened  so  as  to 
resist  the  pressure  and  weight  of  the  water  f 

Answer.  They  are  sometimes  braced  or  stayed  with  rods  or  bars,  V V 


464 


Catechism  of  the  Locomotive. 


and  W W figs.  400,  401  and  402,  extending  from  one  side  to  the  other, 
and  from  the  top  to  the  bottom,  and  angle  or  T-iron  is  also  riveted  to  the 
sides  to  stiffen  them. 


Question  595.  How  is  the  violent  motion  or  swash  of  the  water  in  the 
tank  prevented  ? 

Answer . Transverse  plates,  XXX,  called  “ swash-plates,”  are  placed 


Tenders. 


465 


in  the  tank  to  resist  the  movement  of  the  water  when  the  tender  stops  or 
starts  suddenly. 

Question  596.  How  is  the  tender  connected  to  the  engine  ? 

Answer.  By  the  draw-bar,  Y,  and  coupling-pin,  Z,  fig.  402,  and  also  by 
the  safety  chains,  50,  Plate  IV,  which  are  connected  to  the  eyes,  a a,  figs. 
403  and  404. 

QUESTION  597.  In  what  respect  do  the  tender  trucks  differ  from  the 
engine  truck  ? 

Answer.  Chiefly  in  having  the  journal-bearings  and  frames  outside 
of  the  wheels. 

QUESTION  598.  Why  are  the  bearings  placed  outside  instead  of  between 
the  wheels? 

Answer.  Because  if  they  are  outside  they  are  then  more  accessible 
than  if  they  are  between  the  wheels,  and  the  oil-boxes  on  the  axles  can 
be  entirely  closed  over  the  ends  of  the  axles,  so  that  no  oil  can  leak  out  at 
that  end,  whereas  if  the  boxes  are  inside,  they  must  be  left  open  at 
both  ends.  When  the  boxes  are  on  the  outside,  they  can  be  oilad^or  a 
journal-bearing  can  be  removed  and  a new  one  put  in  its  place,  \^lm  much 
less  difficulty  than  if  the  boxes  are  on  the  inside  of  the  wheels.  The  only 
reason  why  the  bearings  of  engine  truck-axles  are  placed  inside?  the  wheels 
is  because  they  would  be  in  the  way  of  the  cylinders  if  they  were  outside. 

Question  599.  How  are  the  axle-boxes  for  the  tender  axle  constructed ? 

Answer.  Their  construction  is  similar  to  that  of  a car  axle-box,  a stand- 
ard form  of  which  is  represented  in  figs.  408,  409,  and  410.  Figr408  is  a 
section  lengthwise  of  the  axle,  fig.  409  a sectional  plan,  and  fig.  410  a sec- 
tion crosswise  of  the  axle.  A is  the  journal  of  the  axle,  which  is  enclosed 
by  a cast  iron  box,  K K,  which  is  open  in  front  and  at  the  bac£.  The 
front  has  a cover,  H,  which  is  either  fastened  by  a spring,  as  shown  in  the 
illustrations,  or  is  bolted  to  the  box.  The  axle  enters  the  box  from  the 
back,  /,  and  has  either  a wood  or  leather  packing,  f f,  called  a dust-guar dr 
to  keep  the  dust  from  getting  in  and  the  oil  from  leaking  out  of  the  box. 
D is  a brass  journal-bearing  which  rests  against  a cast  iron  bearing 
piece  or  key , E , which  is  put  in  so  that  by  removing  it  through  the  open- 
ing, F,  the  brass  bearing  can  be  raised  up  high  enough  to  clear  the  col- 
lar, G,  on  the  end  of  the  axle  and  thus  be  removed  in  the  same  way.  The 
lower  portion,  Z,  of  the  box  under  the  axle  is  usually  filled  with  cotton  or 
woolen  waste  saturated  with  oil.  This  constantly  presses  against  the  axle, 
and  thus  keeps  it  oiled. 

QUESTION  600.  How  are  the  tender  trucks  constructed? 


466 


Catechism  of  the  Locomotive. 


Answer.  They  are  made  of  various  patterns,  some  of  which  have 
wooden  frames,  but  they  are  now  usually  made  of  iron.  The  truck  illus- 
trated in  figs.  400,  402  and  403  is  made  of  iron,  and  is  very  similar  to  the 
four-wheeled  engine  truck  which  has  been  illustrated,  excepting  as  pointed 
out,  that  the  frames  and  journal-bearings  are  outside  the  wheels  instead 
of  between  them. 


Fig.  409. 

Tender  Truck  Journal-Box. 

Question  601.  How  are  the  tenders  supported  on  the  trucks  ? 

Answer.  Usually  they  rest  on  the  centre-plate,  b,  fig.  402,  of  the  front 
truck  and  on  bearings,  c,  fig.  400,  on  the  frames  on  each  side  of  the  back 


Fig.  408. 


Tenders. 


4G7 


track.  This  arrangement  gives  three  bearing  points,  the  advantages  of 
which  have  been  explained  in  Chapter  XX.  A truck  which  supports 
the  load  which  it  carries  in  the  centre  is  said  to  be  centre-bearing , and  if 
the  load  is  carried  on  each  side,  side-bearing . 

Question  602.  How  are  the  brakes  applied  to  the  tender  ? 

Answer.  They  are  often  applied  to  one  truck  alone,  but  both  trucks 
should  always  have  brakes  attached  to  them. 

Question  603.  What  are  the  chains , d c’  c'  c’,fig.  400  for  ? 

Answer.  These  chains  are  fastened  by  one  end  to  the  corners  of  the 
truck  frames  and  to  the  tender  frames  by  the  other,  so  as  to  hold  the 
trucks  parallel  with  the  track  in  case  they  should  get  off  the  rails. 

QUESTION  604.  What  are  the  brakes  for  and  how  are  they  co?istructed  ? 


Fig.  410.  Tender  Truck  Journal-Box. 


Answer.  The  brakes  are  for  the  purpose  of  stopping  the  locomotive 
and  tender  quickly.  They  consist  of  cast  iron  blocks,  d d , figs.  400,  402  and 
408,  called  brake-blocks  or  brake-shoes,  which  are  attached  to  transverse 
wooden  or  iron  beams,  e <?,  called  brake-beams.  These  beams  are  sus- 
pended from  the  truck  frame  by  the  links  or  hangers,/ /,  called  “brake- 
hangers."  Levers,  g g g g,  called  “ brake-levers ,”  are  attached  to  the 
middle  of  these  beams  by  pivoted  fulcrums.  The  two  levers  on  each 
truck  are  connected  together  by  rods,  h and  h.  The  upper  end  of  one  of 
each  pair  of  these  levers  is  held  fast  by  a pin,  at  i,  and  the  upper  ends, 


468 


Catechism  of  the  Locomotive. 


k k't  of  the  other  lever  are  connected  together  by  a rod,  l fig.  400  ; l'  is 
connected  by  a rod  and  chain,  m,  to  a shaft,  n o.  The  chain  is  wound  on 
the  shaft,  which  is  turned  by  a crank,/,  on  the  upper  end.  By  this  means, 
the  upper  ends,  k k' , of  the  levers  are  drawn  toward  the  shaft,  whiclx 
forces  the  brake  blocks  against  the  wheels.  A piston  in  the  cylinder,  rr 
is  also  connected  with  one  of  the  brake-levers.  The  piston  is  operated  by 
compressed  air,  the  action  of  which  is  fully  explained  in  Chapter  XXVI 
on  air  brakes. 


CHAPTER  XXV. 


WATER-TANKS  AND  TURN-TABLES. 

Question  C05.  How  are  locomotive  tenders  or  tanks  supplied  with 
water  ? 


Answer.  At  suitable  places,  called  water  stations,  along  the  line  of  the 
road,  large  tanks  or  reservoirs,  H H,  fig.  411,  are  located.  These  are 
filled  either  from  natural  streams  which  are  higher  than  the  tanks  and 


470 


Catechism  of  the  Locomotive. 


thus  flow  into  the  latter,  or  else  the  water  is  pumped  in,  either  by  hand  or 
by  horse,  wind,  water,  or  steam  power.  When  there  is  room  for  them, 
these  tanks  are  usually  located  near  the  track,  as  shown  in  fig.  411,  so  that 
the  water  can  be  conducted  by  a spout,  a , direct  from  the  tank  to  the  man- 
hole of  the  tender,  T.  Communication  to  and  from  this  spout  is  opened 
and  closed  by  a valve,  b , inside  of  the  tank,  which  is  moved  from  the  ten- 
der by  a rope,  e,  connected  to  a lever,  f,  and  to  the  valve,  b.  The  spout 
is  usually  attached  to  the  tank  by  a hinged  joint,  so  that  it  can  be  lowered  to 
the  tender  and  then  raised  up  out  of  the  way  of  the  engine  and  train.  It  is 
generally  balanced  by  a counterweight,  suspended  to  one  end  of  a rope,  d, 
which  passes  over  a pulley  and  is  fastened  to  the  spout  at  the  other  end. 
The  tanks  are  now  generally  made  of  wooden  staves  like  a tub  or  pail, 
and  supported  on  a heavy  frame,  c c c,  made  of  wood  as  shown  in  the  en- 
graving, or  on  stone  or  brick  masonry. 

When  there  is  no  room  for  the  tank  or  reservoir  near  the  track,  it  is 
placed  in  any  convenient  position  at  some  distance  from  it,  and  the  water 
is  then  conveyed  by  an  underground  pipe  to  the  place  where  the  locomo-? 
tive  must  take  water.  At  the  end  of  this  pipe  what  is  called  a stand-pipe 
or  water-crane,  fig.  412,*  is  located.  This  consists  of  a vertical  pipe,  A , 
with  a horizontal  arm,  B , which  is  made  so  as  to  swing  around  over  the 
man-hole  of  the  tender  when  the  latter  is  to  be  filled  with  water.  In  some 
cases  the  horizontal  arm  alone  swings  around,  but  in  others  the  vertical 
pipe  turns  with  the  horizontal  one  in  a joint,  C,  underneath  the  surface  of 
the  ground.  The  latter  plan  is  thought  to  be  preferable  to  the  first,  as  the 
pipe  is  less  liable  to  freeze  fast  in  the  joint  when  the  latter  is  underground 
than  when  it  is  exposed  above.  A suitable  valve,  D,  is  also  attached  to 
the  pipe  below  ground,  so  that  the  stream  of  water  can  be  turned  off  or 
on  at  pleasure  by  the  lever,  E,  which  is  connected  by  rods  to  the  valve. 

Question  606.  What  effect  does  the  use  of  impure  water  have  on  a 
locomotive  boiler  ? 

Answer.  The  use  of  impure  water,  or  that  which  contains  a consider- 
able amount  of  mud  or  solid  matter  mixed  with  it,  or  in  suspension,  as  it 
is  called,  or  has  lime  or  other  mineral  substances  chemically  combined 
with  it,  will  very  soon  coat  the  inside  of  the  boiler  with  a covering  of 
scale,  which  is  a very  bad  conductor  of  heat,  and  consequently  the  boiler 
is  much  less  efficient,  and  much  more  heat  is  wasted  than  if  the  heating 
surfaces  were  clear.  Besides  this  loss  of  efficiency,  when  boiler-plates  are 

* The  engraving  illustrates  a stand-pipe  made  by  the  Sheffield  Velocipede  Car  Co.,  of  Three 
Rivers,  Mich. 


Fig.  412.  Water-Crane. 


472 


Catechism  of  the  Locomotive. 


covered  with  non-conducting  scale,  they  are  much  more  liable  to  be  injured 
by  the  action  of  the  fire  than  when  the  water  comes  directly  in  contact 
with  the  metal  of  the  plates.  Some  water,  too,  has  a corroding  effect  on 
the  metal  of  the  boiler  which  is  very  destructive. 

Question  607.  What  considerations  should  determine  the  source  from 
'which  a supply  of  water  should  be  drawn  ? 

Answer.  The  first  must  of  course  be  its  convenience  to  the  point  where 
the  water  is  to  be  used  ; but  more  attention  should  be  given  to  the  quality 
of  the  water  than  it  ordinarily  receives.  The  location  where  a water-tank 
must  be  having  been  decided  upon,  every  possible  available  source  of 
supply  should  be  sampled,  and  analysis  made  of  each  of  the  samples  and 
the  corrosive  substance  which  it  contains,  and  the  solid  residue  which  is 
left  after  the  water  is  evaporated  should  be  determined.  This  having  been 
done,  the  source  which  contains  the  least  corrosive  or  scale-making  ma- 
terial should  be  chosen.  In  general  running  streams  are  much  better  than 
any  other  sources.  Wells  very  rarely  are  good  sources  of  supply.  Much 
expense  can  be  saved  in  boiler  repairs  and  in  the  fuel  account  by  a little 
judicious  expenditure  of  money  to  secure  a supply  of  good  water.  On 
many  of  the  older  railroads  an  examination  of  all  possible  sources  of  -water- 
supply  is  now  being  made,  with  a view  to  abandoning  a large  number  of 
the  old  sources,  and  securing  others  near  by  which  contain  much  less 
scale-making  material.  If  this  had  been  done  when  the  roads  were  first 
located,  much  extra  cost  for  fuel  and  repairs  would  have  been  saved. 

Question  608.  How  can  the  relative  amount  of  incrustating  substances 
in  different  kinds  of  water  be  deter jnined  ? 

Answer.  The  relative  quantity  of  solid  matter  or  mud  which  is  held  in 
suspension  can  be  at  least  approximately  determined  by  simply  filling 
vessels,  say  large  clear  glass  bottles,  with  different  kinds  of  water  and 
adding  a few  drops  of  water  of  ammonia,  and  letting  them  stand  for  some 
time  until  the  solid  matter  settles  to  the  bottom. 

A comparison  of  one  water  with  another,  as  to  its  scale-making  proper- 
ties, may  readily  be  obtained  by  having  samples  of  the  different  waters  in 
some  small  bottles  of  the  same  size,  adding  to  them  water  of  ammonia 
until  each  is  distinctly  alkaline,  and  then  a little  phosphate  of  soda.  This 
causes  a precipitation  of  the  iron,  alumina,  lime  and  magnesia  in  the  water 
as  phosphates,  and  the  bulk  of  the  precipitate  indicates  the  relative 
amount  of  scale-making  material.  This  test  is,  of  course,  crude,  and 
would  hardly  take  the  place  of  a good  chemical  analysis,  but  it  is  much 
better  than  nothing. 


Water-Tanks  and  Turn-Tables. 


478 


When  the  water  of  ammonia  cannot  easily  be  procured,  an  experiment 
may  be  tried  in  the  same  way,  by  dissolving  common  white  soap,  or  other 
pure  soap,  in  a goblet  of  pure  water,  and  then  stirring  into  the  glasses  of 
water  to  be  tested  a few  teaspoonfuls  of  this  solution.  The  comparative 
amount  of  scale-making  material  in  the  water  will  be  shown  by  the 
amount  of  coagulated  matter  which  will  be  thrown  down. 

Question  609.  What  are  the  most  commonly  occurring  corrosive  ma- 
terials in  waters  used  in  boilers  ? 

Answer.  The  most  commonly  occurring  corrosive  materials  are  sul- 
phates of  iron  and  alumina  and  chloride  of  magnesium.  The  former  are 
universal  constituents  of  mine  drainage.  The  latter  occurs  most  frequently 
along  the  sea-shore.  In  addition  to  this  many  waters  which  drain  from 
mines  contain  large  amounts  of  free  sulphuric  acid.  If  any  mine  drainage 
gets  into  the  water-supply  at  any  place,  the  use  of  that  water  should  be 
abandoned  if  possible.  Also  in  wells  along  the  sea-shore,  or  on  the  banks 
of  rivers  affected  by  the  tides,  chloride  of  magnesium  is  a frequent  con- 
stituent, and  often  causes  serious  corrosion  of  boilers.* 

Question  610.  How  are  locomotive  tenders  supplied  with  coal? 

Answer.  This  is  done  in  a variety  of  ways.  Sometimes  the  coal  is 
shoveled  from  cars  alongside  of  the  tender,  but  this  is  a slow  and  laborious 
method.  In  other  cases  iron  buckets  are  filled  with  coal  at  stations  and 
then  are  hoisted  by  cranes  and  swung  over  the  tenders.  They  are  then 
either  tipped  or  a door  in  the  bottom  is  opened  and  the  contents  are 
emptied  into  the  tender.  In  still  other  cases,  small  cars  are  loaded  with 
coal  and  are  run  on  platforms  which  are  high  enough,  so  that  the  contents 
of  the  cars  can  be  dumped  into  the  tender.  Fig.  413  represents  a side 
view  and  fig.  414  a transverse  section  of  what  is  called  a coal  chutep  It 
consists  of  an  inclined  track,  A A,  which  leads  to  an  elevated  level  track, 
B B,  which  extends  through  a building,  H H.  On  one  or  both  sides  of 
this  track  the  building  has  receptacles  or  “ pockets,”  as  they  are  called,  F, 
fig.  414,  to  receive  the  coal  from  the  cars.  These  pockets  have  inclined 
floors,  G,  and  are  closed  by  doors,  D D,  figs.  413  and  414.  Each  pocket 
also  has  a spout  or  “ apron”  E,  which  can  be  extended  out  over  the  tender, 
as  shown  in  fig.  414.  These  aprons  are  hinged  at  /,  and  can  be  folded  up 
out  of  the  way  when  not  in  use.  The  pockets  are  filled  with  coal,  and 

* The  above  information  about  water  was  furnished  by  C.  B.  Dudley,  Chemist,  of  the  Penn- 
sylvania Railroad  Company. 

t The  figures  represent  a coal  chute  made  and  patented  by  Messrs.  Williams,  White  & Co., 
of  Moline,  111. 


Fig.  415.  Wrought-Iron  Turn-Table.  Scale  % in.=l  ft. 


Fig.  416.  Plan  of  Turn-Table.  Scale  % in.=l  ft. 


Water-Tanks  and  Turn-Tables. 


477 


when  a tender,  T,  is  to  be  supplied  it  is  run  on  a track  alongside  of  the 
coal  chute  opposite  to  one  of  the  pockets.  The  apron,  E,  is  then  lowered 
and  the  door,  D,  opened,  and  the  contents  of  the  pocket  are  emptied  into 
the  tender  in  a few  seconds. 

In  some  cases  coal  chutes  are  furnished  with  scales  for  weighing  the 
coal  supplied  to  tenders. 

Question  611.  How  are  locomotives  turned  around  on  the  track? 

Answer.  The  most  common  means  employed  for  that  purpose  is  a: 
turn-table , of  which  fig.  415  is  a side  elevation,  fig.  416  a plan,  and  fig.  417 
a cross-section  through  the  centre  on  the  line,  a b*  It  consists  of  two 
heavy  beams  or  girders  made  of  wood,  cast  or  wrought-iron,  placed  side 
by  side,  and  resting  on  a pivot,  P,  fig.  417,  in  the  centre,  on  which  they 


Fig.  417.  Section  of  Centre  of  Turn-Table.  Scale  34  in.=l  ft. 

turn.  They  are  placed  in  a circular  pit,  C C (part  of  which  is  omitted  in* 
the  plan),  below  the  level  of  the  track,  A A,  so  that  when  rails  are  laid  in. 
the  ordinary  way  on  top  of  the  girders  they  will  be  exactly  level  with  the. 
track  which  leads  up  to  the  pit.  By  turning  the  girders  on  the  central 
pivot  so  that  the  rails  will  come  exactly  in  line  with  the  permanent  track. 
which  leads  up  to  the  pit,  the  locomotive  can  be  run  on  the  turn-table,, 
which  is  then  revolved  a half-revolution,  which  of  course  reverses  the 
position  of  the  locomotive  and  brings  it  opposite  the  permanent  track  so 
that  it  can  be  run  off  from  the  table.  In  order  to  prevent  the  girders  from- 


* Designed  by  A.  P.  Boiler,  C.  E.,  71  Broadway,  New  York. 


Water-Tanks  and  Turn-Tables. 


479 


tipping  down  when  the  engine  first  runs  on  or  off  of  the  turn-table,  w’heels,. 
IV  W,  are  placed  at  their  outer  ends  which  run  on  a circular  track,  D D, 
and  they  bear  any  inequality  of  weight  that  may  be  thrown  on  either  end 
of  the  turn-table  if  the  locomotive  is  not  equally  balanced  on  the  central 
pivot. 

Fig.  418  represents  a cast  iron  turn-table,  manufactured  by  Messrs. 
Wm.  Sellers  & Co.,  of  Philadelphia. 

Question  612.  How  are  the  central  pivots  of  turn-tables  constructed? 

Answer.  They  usually  consist  of  a vertical  post,  F (shown  in  fig.  417, 
which  is  a transverse  section  through  the  centre  of  the  turn-table,  fig. 
415),  the  end  of  which  has  a hard  cast  iron  or  steel  bearing.  In  some 
cases,  the  weight  rests  on  conical  steel  rollers,  which  revolve  in  a circular 
path  formed  in  the  top  plates,  as  shown  at  a a,  in  fig.  419,  which  is  a lon- 
gitudinal section  through  the  central  point  of  Messrs.  Wm.  Sellers  & Co.’s 


G G 


turn-table.  Sometimes  turn-tables  are  fitted  with  gearing  and  cranks,  but 
if  they  are  made  so  that  the  whole  weight  rests  on  the  centre,  and 
if  they  are  of  sufficient  length  so  that  an  engine  and  tender  can  be  moved 
■on  them  sufficiently  to  be  balanced  over  the  centre,  gearing  will  not  be 
needed  ; but  a simple  lever  fastened  to  the  turn-table  will  be  all  that  will 
be  required  to  turn  the  table  and  the  engine  and  tender  on  it.  The 
tables  should  be  of  such  a diameter  or  length  across  the  centre  as  will 
enable  the  class  of  engine  in  use  on  any  road  to  be  balanced.  With  light 


480 


Catechism  of  the  Locomotive. 


engines  a table  50  feet  in  diameter  is  large  enough ; with  the  long,  heavy 
engines  now  used  on  the  great  trunk  lines,  an  engine  and  tender  quite  fill 
up  the  entire  length  of  50  feet,  leaving  no  margin  for  adjustment.  In 
such  cases  a table  60  feet  in  diameter  should  be  employed.  These  large 
tables  are  also  made  heavier  in  proportion.  When  the  engine  and  tender 
is  balanced  over  the  centre  pivot,  one  man  can  turn  the  loaded  table  with 
ease. 

In  setting  up  turn-tables  it  is  necessary  that  the  foundation  at  the  centre, 
upon  which  the  pivot  rests,  should  be  of  the  most  substantial  character, 
so  as  not  to  be  liable  to  settle.  The  circular  track,  which  may  be  made 
of  light  rails,  which  weigh  about  28  or  80  lbs.  to  the  yard,  should  be  level, 
and  the  table  should  be  so  adjusted  as  to  swing  clear  of  the  circular  track 
when  loaded.  The  pit  required  is  quite  shallow  near  the  edge  and 
deepens  toward  the  centre,  and  should  be  properly  drained  to  prevent 
water  from  standing  in  it.  Provision  is  made  for  covering  the  entire  pit 
by  a platform  turning  with  the  table,  but  this  should  be  avoided  when- 
ever possible,  as  the  best  constructed  cover  does  offer  some  resistance  in 
turning.  Even  in  roundhouses,  where  a covered  pit  might  be  considered 
preferable  as  presenting  a smooth  floor  for  crossing  in  any  direction,  it  has 
been  found  advisable,  in  view  of  the  greatest  ease  in  turning  and  the 
facility  offered  by  the  open  pit  for  cleaning,  to  dispense  with  the  cover. 
The  centre  of  the  table  must  be  kept  clean  and  well  oiled,  say  with  best 
sperm  or  lard  oil  and  tallow  of  such  a consistency  as  not  to  harden  in 
cold  weather.  The  top  cap  at  the  centre  is  held  in  place  by  bolts,  G G,  figs. 
417  and  419.  These  bolts  take  the  entire  weight  of  the  table  and  load  ; 
by  slacking  off  the  bolts  the  table  can  be  lowered  on  the  wheels  on  the 
circular  track  and  the  cap  lifted  off  to  gain  access  to  the  bearings.  This 
should  be  opened,  examined  and  cleaned  at  least  once  every  three  months. 

Question  618.  Is  there  any  other  method  of  turning  locomotives? 

Answer.  Yes;  what  is  called  a Y is  sometimes  used.  This  consists  of 
a system  of  tracks  laid  somewhat  in  the  form  of  the  letter  Y,  as  shown  in 
fig.  420,  in  which  A B is  the  main  track  with  two  curves,  A a C and  B b C, 
laid  as  shown.  If  it  is  desired  to  turn  a locomotive  which  is  standing  in 
the  position  of  the  dart,  A,  it  is  run  on  the  curve,  A a C,  to  the  position 
of  the  darts,  a and  C.  It  is  then  run  backward  from  C on  the  curve,  C b 
B,  as  represented  by  the  dart,  b,  and  when  it  reaches  the  main  track  in 
the  position  of  the  dart,  B,  it  is  evident  that  its  position  will  be  reversed 
from  that  in  which  it  was,  at  A,  as  is  shown  if  we  compare  the  direction 
of  the  dart,  A,  with  that  of  B. 


Water-Tanks  and  Turn-Tables. 


4M 


Fig.  420.  The  Y System  for  Turning  Locomotives, 


CHAPTER  XXVI. 


THE  WESTINGHOUSE  AIR-BRAKE. 

Question  614.  What  are  the  brakes  on  locomotives , tenders , and  cars 
for? 

Answer.  The  brakes  are  for  the  purpose  of  reducing  the  speed  of  such 
vehicles,  or  stopping  them  quickly  when  they  are  moving. 

Question  615.  How  are  brakes  usually  constructed  and  operated? 

Answer.  The  brakes  which  are  most  commonly  used  on  railroads  con- 
sist of  metal  or  sometimes  wooden  shoes,  which  are  attached  to  transverse 
beams,  and  suspended  so  that  the  shoes  can  bear  or  rub  against  the 
treads  of  the  wheels.  The  beams  are  connected  to  levers,  and  the  levers 
are  connected  together  by  rods  and  by  a chain  to  a windlass,  which  is 
wound  up  by  a crank  or  hand  wheel,  and  the  brake-shoes  are  thus  pressed 
against  the  treads  of  the  wheels,  and  the  friction  which  is  produced 
resists  the  motion  of  the  vehicle  and  causes  it  to  run  slower  or  stops  it. 

Question  616.  What  difficulty  is  encountered  in  using  brakes  of  this 
kind  which  are  applied  by  hand? 

Answer.  In  cases  of  danger  it  takes  too  much  time  to  apply  them.  If 
a fast-running  train  encounters  any  obstacle  or  obstruction  on  the  track 
the  brakes  cannot  be  applied  quickly  enough  to  stop  the  train  in  time  to 
avoid  an  accident. 

Question  617.  What  was  the  air-brake  designed  for? 

Answer.  It  was  designed  to  apply  brakes  quickly  by  means  of  com- 
pressed air  instead  of  hand  power,  and  also  to  place  the  control  of  the 
brakes  in  the  hands  of  the  locomotive  engineer. 

Question  618.  How  were  the  first  air-brakes  co7istructed? 

Answer.  The  first  air-brake  designed  by  Mr.  Westinghouse  consisted 
of  an  air-pump  on  the  locomotive,  driven  by  steam,  for  compressing  the 
air,  and  a reservoir  on  the  locomotive  or  tender  for  holding  the  compressed 
air.  The  tender  and  each  car  had  a cylinder  and  piston  underneath  its 
body,  the  pistons  being  connected  to  the  brake-levers.  Each  car  had  a 
pipe,  called  a brake-pipe,  extending  its  whole  length  and  connected  to  the 
brake-cylinder,  the  pipes  on  adjoining  cars  and  the  tender  being  connected 


The  Westinghouse  Air-Brake. 


483 


together  by  flexible  hose.  The  brake-pipe  under  the  tender  was  connected 
to  the  air  reservoir  and  had  a valve,  by  which  communication  could  be 
opened  or  closed  between  the  pipe  and  the  reservoir.  The  latter  was 
pumped  full  of  air  of  a pressure  of  about  45  lbs.  per  square  inch.  When 
It  was  desired  to  apply  the  brakes,  communication  was  opened  between 
the  air  reservoir  and  the  train-pipe.  The  compressed  air  in  the  reservoir 
then  flowed  through  the  train-pipes  to  the  cylinders  and  forced  the  pistons 
outward.  The  force  exerted  on  the  pistons  was  communicated  to  the 
brake-levers,  thus  pressing  the  brake-shoes  against  the  wheels.  This  form 
of  brake  has  been  named  the  “ straight  ” air-brake  by  the  men  who  used  it. 

Question  619.  What  difficulty  was  encountered  in  using  this  form  of 
brake? 

Answer.  If  the  train  consisted  of  more  than  a few  cars,  considerable 
time  was  required  for  the  air  to  flow  from  the  reservoir  through  the  brake- 
pipes  to  the  cylinders.  When  danger  is  imminent  a very  small  fraction  of 
time  is  of  the  utmost  importance.  It  was  therefore  found  that  this  form 
of  air-brake  would  not  act  quickly  enough  in  case  of  danger,  and  it  was 
also  found  that  in  the  event  of  the  bursting  of  a coupling  hose  or  brake- 
pipe,  the  supply  of  air  to  the  cars  behind  the  rupture  was  cut  off  and  the 
air  in  the  reservoir  escaped,  and  the  brakes  would  not  work.  As  such 
ruptures  were  liable  to  occur  at  times  when  the  brakes  were  most  needed, 
it  was  a serious  defect. 

The  couplings  of  the  hose  between  the  cars  had  check-valves,  which 
closed  when  they  were  uncoupled,  but  when  a train  broke  in  two  the 
brakes  could  be  applied  to  the  front  end  of  it  only  and  would  stop  it, 
whereas  they  had  no  control  over  the  back  portion,  which  was  liable  to 
run  into  the  front  part  and  thus  cause  a dangerous  collision. 

Question  620.  How  were  these  difficulties  overcome  ? 

Answer.  To  meet  these  difficulties,  Mr.  George  Westinghouse,  Jr.,  de- 
vised and  in  1872  patented  what  is  called  the  Automatic  Air-Brake,  and 
which  is  now  generally  used  on  passenger  and  to  some  extent  on  freight 
trains  in  this  country. 

Question  621.  How  is  the  automatic  air-brake  constructed? 

Answer.  Its  general  arrangement  is  shown  in  Plate  VI,  which  repre- 
sents a side  view  and  plan  of  a locomotive,  tender,  and  car,  and  a view 
looking  at  the  back  end  of  the  locomotive.  The  pipes  and  reservoirs  are 
colored  blue,  and  the  other  parts  of  the  brake  are  colored  red.  In  fig.  A 
the  running  gear  of  the  tender  and  car  are  shown  in  section  ; fig.  B is  an 
end  view  looking  at  the  back  end  of  the  engine,  and  in  fig.  C the  bodies 


484 


Catechism  of  the  Locomotive. 


of  the  tender  and  car  are  supposed  to  be  removed  and  are  indicated  by- 
dotted  lines  only. 

The  automatic  brake  consists  of  the  same  parts  as  the  first  or  “ straight  ” 
air-brake  had — that  is,  an  air-pump,  1,  figs.  A,  B and  C ; a main  reservoir, 
2,  a brake-pipe,  3 3,  3'  3',  3"  3",  for  conveying  air  from  the  main  reservoir 
to  the  tender  and  each  car  behind  it ; cylinders  and  pistons,  4,  4',  4",  on 
each  vehicle  of  the  train,  which  are  connected  to  the  brake-levers  and 
brake-beams  as  shown,  and  as  will  be  more  fully  explained  further  on. 
The  brake-pipe  has  a flexible  hose  connection,  5 5'  5",  between  adjoining 
vehicles  which  have  suitable  couplings  for  connecting  and  disconnecting 
the  hose.  Instead  of  having  but  one  air  reservoir  on  the  engine  or  tender 
for  holding  compressed  air,  the  automatic  brake  has  besides  separate  or 
auxiliary  reservoirs,  6 6'  6",  on  the  locomotive,  the  tender,  and  each  car. 
The  air  pump  is  connected  to  the  main  reservoir  by  a pipe,  7 7.  The 
main  reservoir  is  connected  by  another  pipe,  8 8 8,  to  the  engineer’s  brake- 
valve,  9.  The  brake-pipe,  3 3'  3",  is  connected  to  the  engineer’s  valve  and 
extends  back  under  the  tender  and  cars,  and,  as  already  explained,  is  con- 
nected together  between  the  different  vehicles  by  hose,  5 5'  5",  and  to  the 
auxiliary  reservoirs  by  pipes,  10  10'  10",  and  the  auxiliary  reservoirs  are 
connected  to  the  brake  cylinders  by  other  pipes,  11  11'  11".  The  pipes,. 
10  10'  10"  and  11 11'  11",  communicate  with  the  auxiliary  reservoirs  through, 
valves,  12  12'  12",  called  triple-valves,  whose  construction  and  operation, 
will  be  explained  further  on. 

The  cylinders,  4 4'  4",  have  pistons  which  are  connected  to  a system  of 
brake-levers  shown  in  the  engravings.  These  levers  are  connected  to  the 
brake-beams,  13'  13",  which  have  shoes,  15  15'  15",  on  their  ends  that  bear 
against  the  treads  of  the  wheels. 

Question  622.  How  does  the  automatic  air-brake  operate  ? 

Answer.  Its  operation  is  as  follows : Before  the  train  starts  steam  is  let 
on  to  the  air-pump,  which  then  pumps  or  compresses  air  which  passes 
into  the  main  reservoir,  2,  through  the  pipe,  7 7.  Communication  is  then 
opened  by  means  of  the  engineer’s  valve,  9,  between  the  pipe,  8 8,  which 
is  connected  to  the  main  reservoir  and  the  brake-pipe,  3 3'  3". 

The  compressed  air  then  flows  from  the  main  reservoir  through  the 
pipe,  8 8,  engineer’s  valve,  9,  and  brake-pipe,  3 3'  3",  thence  through  the 
branch  pipes,  10  10'  10",  and  triple-valves,  12  12'  12",  to  the  auxiliary  reser- 
voirs, 6 6'  6".  When  the  reservoirs  and  brake-pipe  are  filled  with  com- 
pressed air  of  about  70  lbs.  pressure  per  square  inch,  the  train  is  ready  to* 
start. 


The  Westinghouse  Air-Brake. 


485 


The  triple-valves  are  constructed  so  that  as  long  as  the  brake-pipe  is 
filled  with  compressed  air  communication  between  the  auxiliary  reservoirs, 
6 6'  6",  and  the  brake-cylinders,  4 4'  4",  is  closed,  but  as  soon  as  the  pres- 
sure in  the  brake-pipe  is  reduced  the  triple-valves  open  communication 
between  the  auxiliary  reservoirs,  6 6'  6 ",  and  the  brake-cylinders,  4 4'  4", 
through  the  pipes,  11  IT  IT'.  If  some  of  the  compressed  air  in  the  brake- 
pipe  is  allowed  to  escape,  and  the  pressure  in  it  is  thus  reduced,  the  triple- 
valves will  open,  so  that  the  air  can  flow  from  the  auxiliary  reservoirs  into 
the  brake  cylinders,  which  will  then  force  out  the  pistons  and  apply  the 
brakes.  The  engineer’s  valve  is  constructed  so  that  by  turning  a handle 
shown  at  9,  figs.  B and  C , it  allows  the  air  in  the  brake-pipe  to  escape, 
which  reduces  the  pressure  in  the  pipe.  To  apply  the  brakes,  then,  all 
that  the  engineer  must  do  is  to  turn  the  handle  of  the  valve,  9. 

Question  628.  After  the  brakes  have  been  applied,  how  are  they 
released? 

Answer.  The  handle  of  the  engineer’s  valve,  9,  is  turned  so  that  it 
closes  the  opening  for  the  escape  of  the  air  from  the  brake-pipe,  and  at 
the  same  time  it  opens  communication  between  the  main  reservoir,  2,  and 
the  brake-pipe.  The  compressed  air  stored  in  the  main  reservoir  then 
flows  into  the  brake-pipe,  which  closes  the  triple-valves,  12,  12',  12",  and 
at  the  same  time  they  allow  the  air  in  the  cylinders,  4,  4',  4",  to  escape, 
and  springs  in  the  cylinders  force  the  pistons  inward  and  thus  release 
the  brakes. 

Question  624.  In  practice  what  is  essential  in  applying  automatic 
brakes  ? 

Answer.  In  case  of  danger  it  is  essential  that  the  brakes  should  be 
applied  as  quickly  as  possible,  and  it  is  also  important  that  the  engineer 
should  be  able  to  apply  them  either  gradually  or  as  rapidly  as  circum- 
stances may  require — in  other  words,  that  he  should  be  able  to  regulate 
the  pressure  on  the  brake-shoes  to  stop  slowly  or  quickly,  or  to  increase 
or  release  it  at  pleasure. 

Question  625.  What  is  meant  by  the  automatic  actio?i  of  the 
brakes  ? 

Answer.  It  has  been  explained  that  when  the  pressure  of  the  air  in  the 
brake-pipe  is  reduced,  that  the  triple- valves  open  communication  between 
the  auxiliary  reservoirs  and  the  brake  cylinders  so  that  the  compressed 
air  in  the  reservoirs  then  flows  into  the  cylinders  and  applies  the  brakes. 
If,  therefore,  a coupling  hose  should  burst  or  a train  brake  in  two,  or  any 
other  accident  should  occur  so  that  the  compressed  air  in  the  brake-pipe 


486 


Catechism  of  the  Locomotive. 


would  escape,  the  brakes  would  go  on  of  themselves,  or  be  applied  auto - 
7natically. 

Question  626.  On  what  does  the  automatic  actio7i  of  the  brakes- 
defend? 

Answer.  Chiefly  on  the  triple-valves  and  their  connections  with  the 
auxiliary  reservoirs  and  the  brake  cylinders.  Fig.  421  is  a perspective- 


Fig.  421.  Brake  Cylinder,  Auxiliary  Reservoir  and  Triple-Valve. 

view,  and  shows  one  end  of  the  auxiliary  reservoir  A,  the  cylinder  B, 
with  the  triple-valve,  C,  shown  in  section.  D D is  the  brake-pipe,  to 
which  the  triple-valve  is  connected  by  the  pipe,  E.  The  triple-valve  is 
also  connected  to  the  cylinder,  B,  by  the  pipe,  F F,  and  to  the  auxiliary 
reservoir  by  the  connection,  2. 


The  Westinghouse  Air-Brake. 


487 


Question  627.  How  is  the  triple-valve  constructed , and  what  is  its 
operation  ? 

Answer.  Its  construction  is  shown  in  fig.  422,  which  represents  a sec- 
tion of  the  valve.  It  consists  of  a piston,  5,  which  works  in  a cylindrical 
chamber,  B.  The  rod  or  stem  of  this  piston  engages  with  a slide-valve,  6. 


Fig.  422.  Triple-Valve. 


When  the  engineer’s  valve  is  turned  so  that  there  is  communication  from 
the  main  reservoir  through  the  valve  to  the  brake-pipe,  the  air  from  the 
reservoir  enters  the  triple-valve  at  F,  passes  through  the  four-way  cock, 
18,  by  passages,  a b c,  and  drain-cup,  A , to  the  cylinder,  B,  forcing  the 


488 


Catechism  of  the  Locomotive. 


piston,  5,  into  its  normal  position,  as  shown  in  the  engraving.  The  air 
then  flows  through  a small  groove — shown  at  /,  on  the  left-hand  side  of  the 
piston — past  the  piston  into  the  valve  chamber,  C,  above  it,  and  through 
the  passage,  C k,  and  pipe,  G,  into  the  auxiliary  reservoir,  while  at  the 
same  time  there  is  an  open  communication  from  the  brake-cylinder  to  the 
atmosphere  through  the  pipe,  H ’ and  passages,  d e f g h.  Air  will  thus 
continue  to  flow  into  the  auxiliary  reservoir  until  it  is  filled  with  air  of 
the  same  pressure  as  that  in  the  brake-pipe. 

If,  now,  the  air  in  the  main  brake-pipe,  F,  is  allowed  to  escape  by  means 
of  the  engineer’s  valve,  or  through  accident,  such  as  the  bursting  of  a 
hose,  the  pressure  of  the  air  in  the  brake-pipe,  F,  and  chamber,  B,  below 
the  piston,  5,  will  be  reduced,  whereupon  the  greater  pressure  in  the 
auxiliary  reservoir  and  above  the  piston,  5,  will  force  it  downward  past  the 
groove,  at  /,  and  close  it.  As  the  piston  descends  it  moves  the  slide- 
valve,  C,  with  it  and  uncovers  the  passage,  f,  so  as  to  permit  air  to  flow 
directly  from  the  auxiliary  reservoir  through  the  pipe,  G,  passages,  kfed , 
and  pipe,  H,  into  the  brake-cylinder,  which  applies  the  brake. 

To  release  the  brakes,  air  from  the  main  reservoir  must  be  admitted, 
by  means  of  the  engineer’s  brake-valve,  9,  Plate  IV,  into  the  main  brake- 
pipe,  F,  fig.  422,  from  the  main  reservoir.  As  the  pressure  in  the  main 
reservoir  is  greater  than  that  in  the  auxiliary  reservoirs,  it  forces  the  piston, 
5,  and  slide-valve,  6,  upward  and  back  to  the  position  shown  in  the  en- 
graving, which  allows  the  air  in  the  brake-cylinder  to  escape  through  the 
pipe,  H,  and  passage,  d e f g h. 

To  apply  the  brakes  gently,  a slight  reduction  is  made  in  the  pressure 
in  the  main  brake-pipe,  F,  which  moves  the  piston  down  slowly.  The 
slide-valve,  6,  has  a conical  valve,  7,  called  a graduating  valve , which 
closes  the  passage,  /.  A pin,  n,  in  the  piston-rod  engages  with  the  valve, 
7,  so  that  when  the  piston  first  begins  to  move  downward  it  pulls  the 
valve,  7,  with  it  and  opens  the  passage,  /.  As  the  piston  moves  further 
the  collar,  m , engages  with  the  slide-valve  and  carries  it  downward  with 
it  until  the  port,  /,  is  over  the  passage,  f,  and  the  piston,  5,  comes  in  con- 
tact with  the  graduating  stem,  8,  and  spring,  9.  Air  from  the  auxiliary 
reservoir  then  flows  through  holes  (shown  by  dotted  lines  above  7),  in  the 
slide-valve,  and  then  passes  by  the  passages,/  fed,  to  the  brake-cylinder. 
When  the  pressure  in  the  auxiliary  reservoir  and  in  the  cavity,  C,  above 
the  piston  has  been  reduced,  by  expanding  into  the  brake-cylinder,  until 
the  air  is  of  the  same  pressure  as  that  in  the  main  brake-pipe,  the  piston 
then  pushes  it  up  far  enough  to  close  the  small  valve,  7,  and  thus  cuts  off 


The  Westinghouse  Air-Brake. 


489 


the  air  supply  to  the  brake-cylinder,  and  causes  whatever  pressure  there 
is  in  the  brake-cylinder  to  be  retained  there,  thus  applying  the  brakes  with 
a force  proportionate  to  the  reduction  of  pressure  in  the  brake-pipe.  If 
the  pressure  in  the  brake-pipe  be  again  slightly  reduced  by  the  engineer’s 
valve,  the  valve,  7,  will  again  be  opened  by  the  piston,  5,  and  in  this  way, 
by  repeated  applications,  the  brakes  can  be  applied  gradually  up  to  their 
full  force.  It  will  thus  be  seen  that  it  is  important  to  be  able  to  regulate 
and  control  the  pressure  in  the  main  brake-pipe.  This  is  done  by  means 
of  the  engineer’s  brake  and  equalizing  discharge  valve  which  will  be  de- 
scribed farther  on.  For  making  a quick  stop,  a large  volume  of  air  may 
be  let  out  of  the  train-pipe  which  causes  the  piston,  5,  to  descend  its  entire 
distance,  compressing  the  graduating  spring,  9,  until  it  strikes  the  leather 
joint,  11.  The  upper  edge  of  the  slide  valve,  G,  now  completely  uncovers 
port,/,  permitting  a direct  flow  of  the  air  from  the  reservoir  to  the  brake- 
cylinder,  through  ports,/ e d,  applying  the  brakes  to  their  full  force. 

Question  628.  What  is  the  four-way  cock  ij,  fig.  422, for? 

Answer.  This  cock  is  used  to  shut  off  communication  with  the  brake- 
cylinder  and  auxiliary  reservoir  with  which  it  is  connected,  if  from  any 
cause  it  is  desirable  to  have  the  brake  on  any  particular  car  inoperative. 
To  do  this  the  handle  K , which  is  connected  to  the  plug,  13,  of  the  cock  is 
turned  from  a horizontal  position,  K , to  an  intermediate  one,  shown  by 
the  dotted  lines  at  K" . This  leaves  the  main  brake-pipe  unobstructed  to 
supply  air  to  the  other  vehicles  in  the  train.  If  the  handle,  K , of  the  cock 
is  turned  down  to  the  position  indicated  by  the  dotted  lines  at  M,  there 
will  then  be  a direct  communication  from  the  main  brake-pipe  to  the 
brake-cylinder  through  a channel,  a e d,  and  pipe,  H—  the  triple-valve  and 
auxiliary  reservoir  being  cut  out — and  the  apparatus  can  be  worked  as  a 
non-automatic  brake  by  admitting  air  into  the  main  brake-pipe  and  brake- 
cylinder  to  apply  the  brakes. 

Question  629.  What  is  the  lower  chamber , A,for? 

Answer.  This  is  called  a drain-cup,  and  its  object  is  to  collect  any 
water  which  may  accumulate  in  the  pipes.  The  water  can  be  removed  by 
unscrewing  the  plug,  10,  in  the  bottom  of  the  cup. 

QUESTION  630.  Why  is  it  absolutely  essential  to  have  an  excess  of  pres- 
sure m the  main  reservoir  over  that  in  the  mam  pipe  and  auxiliary  reser- 
voirs ? 

Answer.  When  the  brakes  are  applied,  as  has  been  explained,  the 
piston,  5,  in  the  triple-valve,  fig.  422,  is  forced  down  in  the  cylinder,  B.  To 
release  the  brakes  this  piston  must  be  forced  up  in  the  cylinder  to  the 


Fig.  423. 


The  Westinghouse  Air-Brake. 


491 


Fig.  427. 

Engineer’s  Brake-Valve.  Scale  Y\  in.=l  in. 


492 


Catechism  of  the  Locomotive. 


i 


Engineer’s  Brake-Valve. 


The  Westinghouse  Air-Brake. 


493 


position  shown  in  the  engraving.  To  do  this  promptly  and  with  certainty 
it  is  absolutely  essential  in  long  trains,  and  is  of  great  importance  in  short 
ones,  to  have  an  excess  of  pressure  in  the  main  reservoir,  so  that  when  air 
is  admitted  to  the  brake-pipe  the  pressure  below  the  pistons  in  the  triple- 
valves will  be  considerably  greater  than  that  above  it.  If  it  is  not  con- 
siderably greater  it  may  not  be  sufficient  to  raise  the  pistons  into  the 
position  they  must  occupy  to  release  the  brakes.  The  method  of  increas- 
ing the  pressure  in  the  main  reservoir  will  be  explained  further  on. 

Question  631.  How  is  the  engineer  s brake  and  equalizing  discharge 
valve  constructed , and  how  does  it  operate  ? 

Answer.  The  construction  of  this  valve  is  shown  in  figs.  423  to  432, 
fig.  423  being  a vertical  section  on  the  line,  I V,  of  fig.  424,  the  latter  being 
a plan  with  the  valve,  13,  removed,  and  fig.  426  is  a similar  section  on  the 
irregular  line,  v h e f r 19,  of  fig.  427  ; fig.  427  is  a horizontal  section  just 
below  the  valve,  13,  of  423.  The  pipe,  X,  fig.  423,  connects  with  the  main 
reservoir,  and  Y with  the  brake-pipe.  Fig.  425  is  an  inverted  plan  of  the 
rotary  valve,  13.  This  valve  has  an  opening  or  “ supply  port,”  a (shown 
also  in  fig.  423),  and  a cavity,  c,  in  its  under  side  analogous  to  the  exhaust 
cavity  in  an  ordinary  locomotive  slide-valve.  This  cavity  is  represented 
by  shade  lines  in  the  plan,  and  by  dotted  shade  lines  in  figs.  428  to  432. 
The  valve  has  another  small  port,  j,  which  passes  entirely  through  it — 
as  shown  in  fig.  426  — and  a small  cavity,  d,  fig.  425,  also  indicated  by 
dotted  shade  lines  in  the  various  plans. 

Fig.  428  represents  a plan  of  the  rotary  valve,  13,  on  its  seat,  in  the  posi- 
tion it  would  be  placed  to  release  the  brakes,  and  where  it  would  be  left 
when  the  engine  has  completed  its  run.  To  prepare  for  another  run, 
steam  is  turned  on  and  the  air-pump  is  started,  which  forces  air  into  the 
main  reservoir,  which  is  connected  to  the  engineer’s  valve  by  the  pipe,  X, 
fig.  423.  When  the  rotary  valve  is  in  the  position  shown  in  fig.  428,  the 
supply-port , a,  in  the  valve  is  over  the  cavity,  b,  in  the  valve-seat.  This 
cavity  is  also  shown  in  figs.  423  and  424,  and  in  figs.  428  to  432  the  part 
which  is  uncovered  by  the  port,  a,  is  represented  by  black  shading,  and  that 
which  is  covered  by  the  valve  is  shaded  with  white  dotted  lines.  When  the 
valve  is  in  the  position  shown  in  fig.  428,  the  cavity,  c,  in  its  under  side  is 
over  the  supply  cavity,  b,  and  also  over  the  port,  /,  which  is  connected 
with  the  main  brake-pipe,  Y,  as  shown  in  fig.  423.  When  the  valve  is  in 
the  position  shown,  air  can  flow  from  the  main  reservoir  up  through  the 
pipe,  X,  fig.  423,  into  the  supply  port,  a,  in  the  valve,  and  into  the  cavity, 
b,  in  the  valve-seat,  then  up  into  the  cavity,  c,  in  the  under  side  of  the 


494 


Catechism  of  the  Locomotive. 


valve,  and  from  there  down  into  the  direct  application  and  supply  port,  1 1, 
which  communicates  with  the  main  brake-pipe,  Y,  from  which  it  passes 
to  the  triple-valves  and  through  them  to  the  auxiliary  reservoirs.  When 
the  rotary  valve  is  in  this  position,  the  port,  j,  in  the  valve,  fig.  428,  is 
over  the  port,  e,  figs.  423  and  424,  in  the  seat,  which  is  connected  with  the 
chamber,  D,  as  shown  by  dotted  lines  in  fig.  423.  Air  from  the  main 
reservoir  can  therefore  flow  into  the  chamber,  D,  above  the  piston,  17, 
and  thence  through  the  port,  s,  which  communicates  with  the  pipe,  T (as 
shown  by  dotted  lines,  s s'  s',  fig.  427),  and  thence  to  a small  reservoir,  16, 
Plate  VI,  called  the  “ engineer  s brake-valve  reservoir ,”  which  is  usually 
suspended  under  the  running-board  of  the  engine.  The  purpose  of  this 
reservoir  is  to  add  to  the  volume  of  the  chamber,  D. 

When  the  auxiliary  reservoirs  are  filled  with  compressed  air  the  rotary 
valve  is  then  turned  to  the  II,  or  “ while  running  ” position,  indicated  by  the 
line  II,  in  fig.  424,  and  as  represented  in  429.  In  this  position  the  valve  has 
moved  so  far  that  there  is  no  longer  communication  between  the  supply  port, 
b,  in  the  valve-seat,  the  cavity,  c,  in  the  valve  and  the  port,  l,  in  its  seat.  A 
small  hole,/,  in  the  valve  then  comes  over  the  small  feed-port,/,  in  the 
seat,  which  is  connected  to  the  cavity,  r,  under  the  “feed-valve,”  21,  as 
shown  in  figs.  426  and  427,  so  that  the  air  can  then  flow  from  the  main 
reservoir  through  the  brake-pipe,  X,  port,/,  and  passage,/,  into  the  cavity, 
r,  fig.  427.  The  feed-valve,  21,  is  pressed  down  on  its  seat  by  a spiral 
spring,  20,  which  has  a resistance  equivalent  to  a pressure  of  air  of  about 
20  lbs.  per  square  inch.  When  this  additional  pressure  is  accumulated 
in  the  main  reservoir,  the  feed-valve  is  forced  open,  and  the  air  which 
escapes  passes  through  the  “ feed-port  ” or  channel,  x,  fig.  427,  to  the  port, 
and  thence  to  the  brake-pipe,  Y,  fig.  423.  At  the  same  time  air  can 
pass  from  the  port,  /,  see  fig.  429,  into  the  cavity,  c,  under  the  valve,  and 
thence  down  through  the  “ equalizing  port ,”  g,  in  the  valve-seat,  which,  as 
shown,  by  dotted  lines,  in  fig.  426,  communicates  with  the  cavity,  D,  above 
the  piston,  17.  The  same  pressure  is  therefore  maintained  in  the  chamber, 
D,  that  exists  in  the  feed-port,  jt,  so  that  the  pressure  above  and  below 
the  piston  is  thus  equalized.  The  stem,  o,  of  the  piston,  fig.  423,  forms  a 
small  conical  valve  which  is  seated  above  the  passage,  n,  and  closes  it 
when  down.  The  area  of  the  opening  below  the  valve  is  reduced  by  a 
teat  attached  to  the  stem,  so  as  to  regulate  the  escape  of  air  from  the 
train  pipe  to  the  atmosphere,  through  the  passages,  m n.  The  passage,  ?i, 
communicates  with  the  atmosphere — see  fig.  426 — so  that  if  the  piston  is 
moved  upward  and  opens  the  valve,  n,  it  allows  air  in  the  brake-pipe  to 


The  Westinghouse  Air-Brake. 


495 


•escape.  It  will  thus  be  seen  that  when  the  rotary-valve  is  in  position  II, 
fig.  429,  that  the  same  pressure  is  maintained  in  the  chamber,  D,  fig.  423, 
that  exists  in  the  brake-pipe.  When  the  rotary  valve,  13,  is  in  this  posi- 
tion no  air  can  pass  from  the  main  reservoir  to  the  brake-pipe  until  the 
pressure  in  the  main  reservoir  is  sufficient  to  open  the  feed-valve,  21, 
which  requires  a pressure  of  20  lbs.  per  square  inch.  As  the  pressure  in 
the  brake-pipe  is  exerted  against  the  opposite  side  of  the  valve,  21,  it  will 
require  an  excess  of  pressure  of  20  lbs.  in  the  main  reservoir  over  that  in 
the  brake-pipe  before  the  valve,  21,  will  be  opened,  and  when  it  does  open, 
air  from  the  main  reservoir  will  flow  from  the  pipe,  X (see  figs.  424  and 
427),  port,/,  passage,/",  into  the  cavity,  r,  and  thence  through  the  feed- 
port,  x,  into  the  cavity,  1 I,  and  brake-pipe,  Y.  Consequently,  when  the 
rotary-valve  is  in  the  position  II,  the  pump  will  fill  the  main  reservoir 
with  air  of  a pressure  20  lbs.  greater  than  that  in  the  t^rake-pipe,  the  ob- 
ject of  which  has  already  been  explained,  and  which  is  very  essential  in 
the  operation  of  the  brakes. 

To  apply  the  brakes  for  making  ordinary  stops  at  stations,  or  service 
stops,  as  they  are  called,  the  handle,  8,  fig.  423,  of  the  rotary-valve  is 
turned  into  position  III,  figs.  424  and  430.  When  in  this  position  all  com- 
munication through  the  valve  and  its  seat  is  closed.  The  valve  handle 
should  then  be  moved  to  the  IV  position,  or  that  for  the  “ application  of 
brakes  for  service  stop,”  shown  in  fig.  431.  The  small  exhaust  cavity,  d, 
figs.  425  and  431,  on  the  under  side  of  the  rotary-valve,  13,  then  establishes 
communication  between  the  two  “ prelnninary  exhaust-ports ,”  e and  h, 
figs.  424  and  431,  in  the  valve-seat.  The  first  of  these,  e,  connects  with 
the  chamber,  D,  as  shown  in  fig.  426,  and  the  second,  h,  leads  to  the 
atmosphere  (see  fig.  427).  Air  can  therefore  escape  up  from  the  chamber, 
D,  see  fig.  423,  through  the  passage,  e,  cavity,  d,  and  down  the  passage,  h, 
to  the  atmosphere.  It  will  be  remembered  that  the  chamber,  D,  is  con- 
nected by  the  passage,  s,  s',  and  pipe,  T,  figs.  423  and  427,  with  the  engineer’s 
brake-valve  reservoir,  16,  Plate  VI.  A pressure-gauge,  21,  Plate  VI,  is 
connected  by  a pipe  to  the  branch,  W,  fig.  423,  which  communicates  with 
the  chamber,  D,  through  passage,  s s'. 

The  gauge,  21,  has  two  sets  of  works  in  it,  one  of  them  connected  as 
described,  and  the  other  connected  by  a pipe  to  the  one  which  leads  to 
the  main  reservoir.  The  two  hands  of  the  gauge  thus  indicate  the  pres- 
sure in  the  main  reservoir  and  also  in  the  chamber,  D,  in  the  engineer’s 
brake-valve,  fig.  423. 

In  making  an  ordinary  stop,  after  the  pressure  in  D has  been  reduced 


496 


Catechism  of  the  Locomotive. 


about  8 lbs.,  the  handle  of  the  engineer’s  valve  should  be  restored  to  the 
III,  or  closed  position.  This  reduction  of  pressure  in  D will  cause  the 
air  below  the  piston,  17,  fig.  423,  to  force  it  and  its  stem  upward,  which 
will  open  the  valve  at  n , and  allow  air  in  the  brake-pipe,  Y,  to  escape  to 
the  atmosphere  through  the  ports,  in,  and  passage,  n' , thus  applying  the 
brakes  gently.  This  discharge  of  air  continues  after  the  valve-handle  is 
carried  to  the  III,  or  closed  ” position — which  allows  the  pressure  in  the 
brake-pipe  to  gradually  equalize  itself  through  the  whole  length  of  the 
train — and  the  escape  of  air  from  the  brake-pipe  does  not  cease  until  the 
pressure  in  it  has  been  reduced  slightly  lower  than  that  yet  remaining  in 
the  chamber,  D,  above  the  piston.  The  latter  is  then  forced  downward, 
which  closes  the  outlet  at  n , and  prevents  the  further  escape  of  air,  until 
the  operation  is  repeated,  which  may  be  necessary  to  apply  the  brakes 
with  the  desired  force. 

QUESTION  632.  What  difficulty  in  the  application  of  brakes  is  the  fea- 
ture of  the  engineer  s brake  and  equalizing  valve,  which  has  been  described 
last,  intended  to  overcome? 

Answer.  In  applying  the  brakes,  especially  on  long  trains,  if  the 
engineer,  instead  of  allowing  the  air  to  escape  slowly  from  the  brake- 
pipes,  allows  a considerable  amount  of  air  to  escape  in  a short  time  and 
then  closes  the  valve  suddenly,  the  air  is  exhausted  from  the  front  end  of 
the  brake-pipe  which  applies  the  brakes  on  the  front  cars  before  the  pres- 
sure in  the  pipe  has  equalized  itself.  The  air  in  the  back  end  of  the  pipe 
then  rushes  forward,  and  if  the  valve  has  been  closed  suddenly  this  rush 
of  air  acts  on  the  triple-valves  and  is  liable  to  release  the  brakes  on  the 
front  cars.  To  avoid  this  difficulty,  the  opening  of  the  passage,  h,  figs. 
424  and  426,  in  the  valve-face  is  made  extremely  small,  so  that  the  pressure 
in  the  chamber,  D,  will  not  be  reduced  too  rapidly,  and  the  chamber,  D,  is 
connected  with  the  brake-valve  reservoir,  16,  Plate  VI,  so  that  the  volume 
of  air  which  must  be  discharged  before  the  brakes  are  applied  is  much 
greater  than  that  contained  in  the  chamber,  D.  As  soon  as  the  pressure 
above  the  piston,  17,  fig.  423,  is  reduced  lower  than  that  below  it  and  in 
the  brake-pipe,  Y,  the  piston  moves  upward  slowly  and  opens  the  valve,  o, 
which  permits  the  air  in  the  brake-pipe  to  escape  through  the  passage,  n’ , 
fig.  426.  This  discharge  of  air  continues  after  the  rotary-valve,  13,  has 
closed  the  opening,  h,  for  the  escape  of  air  from  the  chamber,  D,  and  does 
not  cease  so  long  as  there  is  any  difference  in  the  pressure  above  and 
below  the  piston,  and  until  the  pressure  in  the  brake-pipe  has  been  equal- 
ized and  reduced  slightly  lower  than  that  yet  remaining  above  the  piston. 


The  Westinghouse  Air-Brake. 


497 


So  long  as  there  is  more  pressure  below  the  piston  than  above  it  the  valve, 
o,  remains  open,  and  is  closed  very  gradually  as  the  pressure  in  the  brake- 
pipes  is  reduced.  This,  as  has  been  explained,  permits  the  pressure  in  the 
brake-pipe  to  become  equalized,  and  secures  a uniform  application  of  the 
brakes  through  the  whole  length  of  the  train. 

When  the  pressure  in  the  brake-pipe  is  reduced  a little  below  that  above 
the  piston  the  latter  is  forced  down,  and  closes  the  valve,  <?,  which  prevents 
the  further  escape  of  air  until  the  rotary-valve  handle  is  again  moved  to 
the  IV  position,  fig.  431,  and  the  operation  is  repeated. 

Question  633.  How  are  the  brakes  released? 

Answer.  The  rotary-valve  handle,  8,  fig.  423,  is  turned  back  to  the  I 
position,  or  that  “for  releasing  brakes,”  shown  in  fig.  428.  This,  as  already 
described,  allows  air  from  the  main  reservoir  to  flow  up  through  the  pipe, 

X,  fig.  423,  down  through  the  port,  a,  in  the  rotary-valve,  into  the  cavity, 
b,  in  the  valve-seat,  and  from  there  up  into  the  cavity,  c,  in  the  under  side 
of  the  valve,  and  thence  down  into  the  passage,  / /,  and  to  the  brake-pipe, 

Y.  The  pressure  in  the  latter,  as  has  been  explained,  acts  on  the  triple- 
valve, which  closes  communication  between  the  auxiliary  reservoirs  and 
brake-cylinders,  and  allows  the  air  in  the  brake-cylinders  to  escape. 

Question  634.  In  case  of  imminent  danger  or  any  emergency,  how  is 
the  brake  operated? 

Answer.  In  such  an  event  it  is,  of  course,  essential  to  apply  the  brakes 
as  quickly  and  as  forcibly  as  possible.  To  do  this  the  handle  of  the 
rotary- valve  is  moved  to  the  V or  “emergency  stop  position,”  figs.  424  and 
432.  The  chamber,  c,  in  the  under  side  of  the  rotary-valve  then  comes 
over  the  port,  /,  in  the  seat,  which  connects  with  the  brake-pipe  and  also 
over  the  port,  k,  which  communicates  with  the  atmosphere.  This  estab- 
lishes direct  communication  between  the  brake-pipe  and  the  open  air,  and 
permits  the  air  in  the  brake-pipe  to  escape  quickly  through  the  large 
openings  of  the  ports  referred  to. 

QUESTION  635.  Where  is  the  air  pump  for  operating  the  brakes 
usually  located? 

Answer.  It  is  generally  attached  to  the  right-hand  side  of  the  fire-box 
or  further  forward  on  the  boiler.  See  1,  Plate  VI. 

Question  636.  How  is  the  air  pump  constructed? 

Answer.  Fig.  433,  which  represents  a vertical  section  of  such  a pump, 
shows  its  construction.  It  consists  of  a steam  cylinder,  3,  and  an  air 
cylinder,  5.  Both  of  these  cylinders  have  pistons,  11  and  14,  which  are 
connected  together  by  a piston-rod,  11.  Steam  taken  from  the  locomotive 


Fig.  433.  Brake  Air  Pump. 


% 

The  Westinghouse  Air-Brake. 


499 


boiler  is  admitted  to  the  upper  cylinder  by  a pipe,  F,  and  passage,  A.  The 
upper  piston,  11,  is  operated  by  the  steam  pressure  in  the  cylinder,  3,  and 
moves  the  lower  one,  14,  which  compresses  the  air  in  cylinder,  5.  The  steam 
from  the  boiler  enters  the  cylinder,  B,  between  the  two  small  piston- 
valves,  34  and  38.  The  upper  piston,  34  being  of  greater  diameter  than 
the  lower  one,  the  tendency  of  the  pressure  is  to  raise  the  pistons,  unless 
they  are  held  down  by  the  pressure  of  a third  piston,  30,  of  still  greater 
diameter,  which  works  in  a cylinder  directly  above,  34,  and  bears  on  the 
rod,  32.  The  pressure  on  this  third  piston  is  regulated  by  the  small  slide- 
valve,  23,  which  works  in  the  central  chamber,  24,  on  the  top  cylinder- 
head.  This  valve  receives  its  motion  from  a small  rod,  22,  which  is  con- 
nected to  the  valve,  23,  and  extends  into  the  hollow  piston  rod,  11.  The 
small  rod  has  a knob  on  its  lower  end  and  a shoulder,  S,  just  below  the 
top  cylinder-head.  A steam  passage  connects  the  valve  chamber,  24, 
with  the  steam  space,  B,  between  the  pistons,  34  and  38.  The  steam 
acting  on  the  third  piston,  30,  holds  the  piston-valves,  34  and  38,  down 
and  at  the  same  time  steam  enters  the  cylinder,  3,  through  the  openings 
at  40  and  pushes  the  main  piston,  11,  up  in  its  cylinder.  As  the  main 
piston  approaches  the  upper  end  of  the  cylinder,  the  shoulder,  20,  on  the 
piston  strikes  the  shoulder,  S,  on  the  rod,  22,  and  pushes  it  and  the  valve, 
23,  upward.  This  allows  the  steam  in  the  cylinder,  C,  to  escape,  and 
relieves  the  pressure  above  the  piston,  30.  The  steam  pressure  below  the 
piston-valve,  34,  then  pushes  it  and  the  valve,  38,  upward,  which  admits 
steam  into  the  upper  end  of  the  cylinder,  3,  through  the  openings  in  the 
cylinder,  36,  and  also  allows  that  in  the  lower  end  to  escape  through  the 
openings  at  38.  The  piston,  11,  is  thus  forced  down  in  the  cylinder  until 
the  shoulder,  20,  comes  in  contact  with  the  knob  on  the  end  of  the  rod, 
22,  which  moves  the  slide-valve,  23,  and  again  admits  steam  into  the 
cylinder  above  the  piston,  30,  and  the  action  is  repeated.  The  exhaust 
chambers  at  36  and  below  38,  communicate  with  the  pipe,  61,  through 
which  steam  is  exhausted.  This  pipe  is  indicated  by  25,  in  Plate  VI. 

Question  637.  How  is  the  air  cylinder  of  the  air  pump  constructed? 

Answer.  It  has  air  inlets  at  48  and  51  and  conical  valves,  45,  46,  49, 
and  50,  above  and  below  these  inlets.  When  the  piston,  14,  descends  it 
compresses  the  air  below  it,  which  closes  valve  50  and  raises  and  opens  49, 
so  that  the  compressed  air  passes  into  the  chamber,  D,  and  through  the  pipe, 
53 — indicated  by  7,  in  Plate  VI — into  the  main  reservoir.  At  the  same 
time  a partial  vacuum  is  produced  above  the  piston,  which  causes  the 
atmospheric  pressure  below  valve  46  to  raise  it,  thus  allowing  air  to  flow 


500 


Catechism  of  the  Locomotive. 


into  the  cylinder  through  the  air  inlets  at  48.  The  chamber  above  45  is 
connected  with  the  chamber,  D,  and  main  reservoir,  so  that  when  the 
pressure  in  them  is  greater  than  that  below  the  valve,  45,  it  is  forced  down 
on  its  seat  and  closed.  The  reverse  action  takes  place  when  the  piston, 
14,  ascends — that  is,  valve  50  opens  to  admit  air  below  the  piston  and  49 
is  closed  by  the  pressure  above  it.  At  the  same  time  46  is  closed  and  45 
opens,  so  that  the  air  which  is  compressed  above  the  piston  flows  through 
the  valve,  45,  to  the  chamber,  D,  and  thence  into  the  main  reservoir. 

Question  638.  How  is  the  action  of  the  air  pump  regulated? 

Answer.  By  means  of  what  is  called  a pump  governor,  indicated  by 
22,  in  Plate  VI,  and  by  G,  in  fig.  433,  on  the  left-hand  side  of  the  pipe 
connection,  at  A,  and  shown  in  a vertical  section  in  fig.  434. 


Fig.  434.  Brake-Pump  Governor. 

QUESTION  639.  What  is  the  construction  and  action  of  the  pump 
governor  ? 

Answer.  One  end,  23,  of  the  horizontal  pipe,  2 2,  is  connected  to  the 
boiler  and  the  other  end  to  the  pump.  The  chamber,  2 2,  has  a division 
and  a valve,  9,  between  the  two  ends.  The  valve  is  connected  by  a stem, 
7,  to  a piston,  5,  which  bears  on  a spiral  spring,  8.  19  is  a diaphragm 


The  Westinghouse  Air-Brake. 


501 


which  is  pressed  down  by  another  spiral  spring,  18,  which  resists  a pres- 
sure under  the  diaphragm  of  about  70  lbs.  per  square  inch.  A small  coni- 
cal valve,  17,  is  connected  to  the  diaphragm,  and  opens  and  closes  an 
opening  below  it  and  above  the  piston,  5.  The  space  below  the  diaphragm 
is  connected  by  a pipe,  21,  to  the  brake-pipe.  When  the  air  pressure 
below  the  diaphragm  exceeds  70  lbs.  it  raises  it  and  opens  the  valve,  17, 
which  admits  compressed  air  above  the  piston,  5,  which  is  forced  down, 
thus  closing  the  valve,  9,  and  shutting  off  steam  from  the  pump.  The  air 
in  the  chamber  above  the  piston  then  leaks  past  the  piston,  5,  and  escapes 
from  it  into  the  open  air,  through  an  opening  represented  by  dotted  lines. 
When  the  pressure  in  the  brake-pipe,  21,  is  reduced,  the  spring,  18,  closes 
the  valve,  17,  so  that  the  action  of  the  spring,  8,  and  the  pressure  below 
the  valve,  9,  opens  it  and  admits  steam  to  the  pump. 

Question  640.  Haw  are  the  brake-cylinders  and  pistons  constructed  ? 

Answer.  The  construction  of  a brake-cylinder  is  shown  in  section  by 
fig.  435.  It  is  a simple  cylinder  with  a piston,  8,  which  has  leather  pack- 


ing, 9,  and  a piston-rod,  3.  The  piston-rod,  after  being  driven  out  by 
compressed  air,  is  forced  back  again,  when  the  air  is  released,  by  a spiral 
spring,  12,  which  is  wound  around  the  piston-rod. 

To  prevent  the  application  of  the  brakes  from  a slight  reduction  of 
pressure,  caused  by  leakage  in  the  brake-pipe,  an  oval  groove  ¥9¥  inch 
wide,  and  ^ inch  deep,  and  3 inches  long — shown  at  a,  at  the  top  of  the 
piston,  in  fig.  435 — is  cut  in  the  body  of  the  brake-cylinder,  of  such  a 
length  that  the  piston  must  travel  3 inches  before  the  groove  is  covered 
by  the  packing  leather.  A small  quantity  of  air,  such  as  results  from  a 
leak,  passing  from  the  triple-valve  into  the  cylinder,  has  the  effect  of  mov- 


502 


Catechism  of  the  Locomotive. 


ing  the  piston  slightly  forward,  but  not  sufficiently  to  close  the  groove. 
This  permits  the  air  to  flow  out  past  the  piston.  If,  however,  the  brakes 
are  applied  in  the  usual  manner,  the  piston  will  be  moved  forward  beyond 
the  groove,  notwithstanding  the  slight  leak. 

Question  641.  How  are  the  brake-pipes  on  the  locomotive  tender  and 
cars  connected  together  ? 

Answer.  By  flexible  hose,  5 5'  5",  Plate  VI,  between  the  different 
vehicles  in  the  train.  The  hose  are  attached  at  one  end  to  the  brake- 
pipes  and  are  connected  together  between  the  different  vehicles  in  the 
train  by  couplings,  shown  by  figs.  436  and  437.  Cocks,  29'  29",  Plate  VI, 


Fig.  436. 


i 


Fig.  437. 

Hose  Connections. 


are  attached  to  the  ends  of  the  brake-pipes  on  each  car  and  at  the  back 
end  of  the  tender.  The  end  of  the  pipe  which  comes  at  the  end  of  the 
train  can  thus  be  closed  to  prevent  the  air  in  the  brake-pipe  from  escaping. 

Question  642.  What  arrangement  is  made  for  applying  the  brakes 
from  the  inside  of  the  cars  ? 

Answer.  A vertical  pipe  with  a cock  or  valve,  28",  Plate  VI — called  a 
“ conductor  s valve  ” — on  the  upper  end  is  connected  -to  the  brake-pipe  on 
each  car.  By  opening  this  valve  the  air  in  the  brake-pipe  can  escape 
which  applies  the  brakes.  A cord  which  extends  the  whole  length  of  the 


The  Westinghouse  Air-Brake. 


503 


car  is  usually  connected  to  this  valve,  so  that  it  can  be  pulled  from  any 
part  of  the  car. 

Question  643.  How  is  the  moisture  which  condenses  in  the  inside  of 
the  pipes  and  reservoirs  removed? 

Answer.  A cup,  called  a drip-cup,  is  connected  to  the  brake- pipes 
belo  w the  tender,  from  which  the  water  that  collects  in  it  is  drawn  by 
means  of  a cock  in  the  bottom  of  the  cup.  There  are  also  cocks,  20'  20", 
Plate  VI,  attached  to  each  auxiliary  reservoir,  and  when  they  are  opened, 
if  there  is  any  water  in  the  reservoirs  it  can  escape. 


Fig.  439. 


QUESTION  644.  How  are  the  air-brakes  on  the  locomotives  arranged? 

Answer.  The  brake-shoes,  15  15,  are  usually  applied  to  the  driving- 
wheels,  and  are  located  between  these  wheels,  as  shown  in  Plate  VI  and 
fig.  438,  which  is  a side  view,  and  fig.  439  an  end  view,  showing  the 
arrangement  of  the  brakes  in  relation  to  the  wheels.  A brake-cylinder. 


504 


Catechism  of  the  Locomotive. 


A,  is  placed  on  each  side  of  the  engine,  the  piston-rods  of  which  work 
through  the  lower  head.  The  rods  have  cross  or  T-heads,  on  their 
lower  ends,  which  are  connected  by  links,  L L , to  the  cams,  C C.  These 
cams  are  connected  to  the  levers,  F F at  D D.  The  levers  have  break- 
blocks,  G Gy  attached  to  them  by  pins  at  H H.  The  surfaces  of  the  two 
cams  which  are  in  contact  with  each  other  are  eccentric  to  the  centre  of 
the  pins,  D D,  and  when  they  are  pressed  down  by  the  piston,  they  force 
their  lower  ends,  D D,  and  levers,  F F,  outward,  which  presses  the  brake- 
blocks  against  the  wheels.  6,  Plate  VI,  is  the  auxiliary  reservoir  for  the 
engine  or  “ driver-brakes,"  as  they  are  called,  and  12  is  the  triple-valve  by 
which  the  brake  on  the  engine  is  operated.  11  is  the  pipe  which  supplies 
the  driver-brake  reservoir  with  compressed  air,  and  10  is  the  pipe  by  which 
it  is  conveyed  from  the  triple-valve  to  the  break-cylinders,  4 4. 

Question  645.  What  is  meant  by  the  term  “ straight  air-brake  ?" 

Answer.  As  explained  in  answer  to  Question  618,  this  term  is  used  to 
designate  the  first  form  of  the  Westinghouse  air-brake,  in  which  there 
were  no  auxiliary  reservoirs  under  the  cars,  the  compressed  air  being 
stored  in  a main  reservoir  on  the  engine  or  tender,  from  which  it  flowed 
direct  through  the  brake-pipe  to  the  brake-cylinders  under  the  different 
vehicles.  The  brakes  were  released  when  communication  was  closed 
between  the  main  reservoir  and  the  brake-pipe,  and  opened  from  the 
brake-pipe  to  the  atmosphere  by  means  of  the  engineer’s  valve.  When 
“ straight  air”  is  applied  it  flows  direct  through  the  brake-pipe  to  the 
brake-cylinders,  and  the  auxiliary  reservoirs,  triple-valves,  and  pressure- 
retaining  valves  are  not  used,  and  the  brake  has  no  automatic  action. 

Question  646.  How  can  the  automatic  brake  be  used  as  a straight  air- 
brake ? 

Answer.  The  old  form  of  automatic  brake  can  be  converted  into  a 
straight  air-brake  by  simply  turning  the  handle,  K,  fig.  422,  of  the  four- 
way cock  on  the  triple-valve  downward  to  K'n , so  as  to  stand  in  a vertical 
( | ) position  ; the  cock  then  opens  direct  communication  from  the  brake- 
pipe  to  the  brake-cylinders  through  the  channels,  a e d.  With  the  new 
quick-acting  triple-valve,  which  will  be  described  further  on,  the  automatic 
brake  cannot  be  converted  into  a straight  air-brake. 

Question  647.  When  should  the  automatic  brake  be  used  as  a straight 
air-brake  ? 

Answer.  In  case  of  serious  leakage  of  pipes,  or  other  defect  which  pre- 
vents the  use  of  the  automatic  brake,  the  handle  of  the  four-way  cocks  of 
all  the  triple-valves,  excepting  those  on  vehicles  on  which  the  brakes  are 


LIBRARY 

Oh  IH£ 

UNiVERSIT  y of  ILLINOIS 


Fig.  440.  Freight  Car  Brake.  Scale  J4  in.=l  ft. 


The  Westinghouse  Air-Brake. 


505 


cut  out,  should  be  turned  downward,  and  the  train  can  then  be  run  with 
“straight  air  ” to  the  terminus.  It  is  better  to  do  this  than  to  depend 
upon  the  use  of  the  hand-brakes ; but  all  the  brakes  which  are  in  use  (that 


^19 


Fig.  443. 

Freight  Car  Brake.  Scale  in.=l  ft. 

is,  that  are  not  cut  out)  on  a train  must  be  operated  either  by  “straight 
air  ” or  automatically,  as  the  two  systems  will  not  work  together  on  the 
same  train. 


506 


Catechism  of  the  Locomotive. 


Question  648.  How  do  the  air-brakes  for  freight  trains  operate,  and 
how  are  they  constructed ? 

Answer.  The  action  of  brakes  on  freight  trains  is  the  same  as  on 
passenger  trains,  although  the  form  of  construction  is  somewhat  different. 
Fig.  440  is  a side  elevation,  and  fig.  441  an  inverted  plan,  fig.  442  an  end 
view,  and  fig.  443  a transverse  section  of  a freight  car  with  brake  attached, 
and  fig.  444  is  a section  of  the  cylinder  and  auxiliary  reservoir.  The  con- 
struction of  the  cylinder  is  substantially  the  same  as  that  used  on  pas- 
senger trains.  The  auxiliary  reservoir,  10,  is,  however,  made  of  cast  iron, 
and  is  attached  to  the  brake-cylinder  head,  14,  as  shown  in  fig.  444. 

Question  649.  What  provision  is  made  on  freight  train  brakes  for 
descending  long  grades? 


Answer.  What  is  called  a “ pressure-retaining  valve,”  40,  figs.  440  and 
and  442,  is  connected  by  a pipe,  39  39,  with  the  discharge  port  of  the 
triple-valve,  12.  An  enlarged  section  of  this  valve  is  shown  by  fig.  445. 
5 is  the  valve  which  opens  and  closes  the  passage  or  pipe,  b b.  The  valve 
has  a weight,  3,  which  presses  it  down.  A pressure  of  about  15  lbs.  in  the 
pipe,  b b,  is  sufficient  to  raise  this  weight  and  allow  the  air  to  escape  at 
the  opening,  c.  4 4 is  a three-way  cock  which,  in  the  position  shown — 
with  the  handle  horizontal — closes  the  opening,  a,  so  that  the  air  can 
escape  only  under  the  valve,  5,  and  opening,  c.  As  the  valve  is  weighted, 
no  air  can  escape  until  its  pressure  is  sufficient  to  raise  the  weight,  3. 
Consequently,  if  the  handle  of  the  cock  is  turned  to  a horizontal  position 
in  descending  long  grades,  a pressure  of  about  15  lbs.  is  retained  in  the 
brake-cylinder,  which  keeps  the  train  under  control  when  otherwise  the 
brakes  would  be  released  to  recharge  the  reservoirs.  On  slight  grades  or 


The  Westinghouse  Air-Brake. 


507 


a level  the  handle  of  the  cock  should  be  turned  down,  which  opens  com- 
munication between  the  pipe,  b,  and  opening,  a,  which  allows  the  air  to 
escape  freely  from  the  discharge  port,  a , of  the  pressure-retaining-valve. 

Question  650.  What  difficulty  was  encountered  in  operating  air- 
brakes on  long  freight  trains  ? • 


Fig.  445.  Pressure-Retaining  Valve. 


Answer.  In  some  tests  made  with  long  freight  trains  it  was  found  that 
the  triple-valve,  shown  in  fig.  422,  and  which  has  been  described,  in  answer 
to  Question  627,  would  not  apply  the  brakes  as  quickly  as  was  considered 
desirable.  For  that  reason  the  quick  acting  triple-valve  represented  in 
section,  in  fig.  446,  was  designed  by  Mr.  Westinghouse. 

Question  651.  How  is  this  valve  constructed  and  how  does  it  act  in 
ordinary  braking? 

Answer .*  The  outside  shell  or  casing  of  this  valve  has  three  openings, 
R,  S,  and  T.  R is  connected  to  the  auxiliary  reservoir,  S,  to  the  brake- 
cylinder,  and  T to  the  brake-pipe.  The  latter  branch  communicates  by 
means  of  the  passages,  Q D D and  openings,  / /,  with  a cylinder,. B,  in 
which  the  triple-valve  piston,  5,  works.  The  chamber,  C,  on  the  opposite 
side  of  this  piston  contains  a slide-valve,  6,  and  is  in  direct  connection 
with  the  auxiliary  reservoir  through  the  branch,  R,  and  when  the  piston  is 

* Much  of  the  following  description  was  taken  from  one  which  originally  appeared  in 
Engineering. 


508 


Catechism  of  the  Locomotive. 


in  the  position  shown  in  the  engraving,  compressed  air  from  the  brake- 
pipe,  T,  can  flow  through  the  chanels,  Q D D'  /,  and  through  a groove,  E, 
in  the  cylinder  past  the  piston,  5,  until  the  pressure  in  C and  in  the 
auxiliary  reservoir  is  equal  to  that  in  the  train-pipe.  At  the  same  time 


Fig.  446. 

Quick  Acting  Triple-Valve. 


the  branch,  S,  and  the  brake-cylinder  are  connected  to  the  atmosphere 
through  the  passage,  /,  the  port,  H,  the  cavity,  O,  in  the  slide-valve,  6, 
and  the  port,  G,  which  communicates  with  the  open  air.  Fig.  449  repre- 


The  Westinghouse  Air-Brake. 


509 


sents  a plan  of  the  valve  face  with  a sectional  plan  of  the  valve  on  it  in 
the  same  position  as  it  is  shown  in  fig.  446.  The  section  of  the  valve  is 
drawn  on  the  line  X Y,  of  fig.  446.  If,  now,  when  the  slide-valve  is  in  the 
position,  shown  in  figs.  446  and  449,  the  pressure  in  the  train-pipe,  T,  is 
slightly  reduced  by  opening  the  engineer’s  valve,  the  pressure  in  the  cyl- 
inder, B,  will  also  be  reduced,  and  the  piston,  5,  will  be  moved  to  the 
right,  as  shown  in  fig.  450  * by  the  expansion  of  the  air  in  the  auxiliary 
reservoir.  Under  ordinary  circumstances,  however,  the  piston  will  be 
moved  through  only  half  of  its  available  travel,  in  consequence  of  the 
pressure  in  the  reservoir  being  reduced  to  that  in  the  train-pipe  by 
a part  of  the  air  flowing  into  the  brake-cylinder  in  the  following  way  : 
The  stem,  4 4',  of  the  piston  passes  through  the  slide-valve,  6 — the  con- 
nection between  the  two  being  so  made  that  the  piston  can  move  a small 
distance  without  moving  the  valve.  The  slide-valve  contains  a small 
conical  valve,  7,  called  a “graduating  valve ” which  is  seated  in  a cavity 
in  the  valve,  and  is  shown  in  figs.  446,  450,  and  also  in  the  horizontal  sec- 
tion of  the  slide-valve,  fig.  448,  which  is  drawn  on  the  centre  line  of  the 
valve,  7.  This  conical  valve  is  connected  to  the  slide-valve  stem,  4,  4 ',  by 
a pin,  a , shown  by  dotted  lines  on  figs.  446  and  450,  so  that  when  the  pis- 
ton moves,  it  first  carries  with  it  and  opens  the  valve,  7.  This  allows  air 
which  enters  through  the  passages,  P P,  figs.  448  and  450,  to  flow  into  the 
passage,  M.  The  continued  movement  of  the  piston  carries  the  slide- 
valve,  6,  to  the  right  into  the  position  shown  in  fig.  450,  and  also  in  fig.  451 
— the  latter  again  represents  a plan  of  the  valve  face  with  a horizontal  sec- 
tion of  the  valve  drawn  on  the  line,  X Y,  of  fig.  450,  and  it  is  shown  in  the 
same  position  in  451  as  in  fig.  450.  By  comparing  figs.  446  and  449  with 
450  and  451  it  will  be  seen  that  the  movement  of  the  valve  to  the  position 
shown  in  figs.  450  and  451  first  closes  the  connection  of  the  port,  H,  with 
the  atmosphere  through  the  cavity,  O,  and  then  brings  the  port,  Z,  in  the 
valve  over  the  port,  H,  in  the  valve  seat.  The  air  can  then  flow  from  the 
chamber,  C,  and  auxiliary  reservoir  through  the  openings,  P,  passage,  M, 
port,  Z,  port,  H,  and  passage,  Z,  into  the  brake-cylinder,  when  it  acts  on 
the  piston,  and  thus  applies  the  brakes.  As  soon  as  the  pressure  in  C has  ~ 
fallen  slightly  below  that  in  the  brake-pipe,  the  pressure  on  the  opposite 
side,  B,  of  the  piston,  5,  moves  the  latter  slightly  back  and  closes  the 
valve,  7,  and  cuts  off  the  air  supply  to  the  brake-cylinder.  If,  now,  the 


* In  drawing  the  sections  of  the  valve  and  its  seat,  some  liberty  has  been  exercised  in  order  to 
show  how  the  valve  acts.  The  sections  are  not  strictly  correct,  but  they  thus  show  the  opera- 
tion of  the  valve  more  plainly  than  they  would  if  they  represented  the  valve  exactly. 


Fig.  450. 


Fig.  451. 


The  Westinghouse  Air-Brake. 


511 


pressure  in  the  brake-pipe  be  again  slightly  reduced  by  the  engineer’s 
valve,  the  valve,  7,  will  again  be  opened  by  the  piston,  5,  and  in  this  way 
by  repeated  applications  the  brakes  can  be  applied  gradually  up  to  the 
maximum  force  which  would  be  possible  when  the  pressure  is  equalized  in 
the  cylinders  and  auxiliary  reservoirs. 

Question  652.  How  does  the  triple-valve,  shown  in  fig.  44.6,  act  in 
making  an  emergency  stop  in  case  of  danger  ? 

Answer.  If  the  locomotive  runner  opens  the  brake- valve  wide  the 
pressure  in  the  brake-pipe  will  be  so  far  reduced  that  the  piston,  5,  will 
move  to  the  extreme  limit  of  its  travel,  and  will  seat  itself  against  the 
leather  ring,  23,  fig.  446,  this  opens  the  valve,  7,  and  moves  the  slide- 
valve,  6,  to  the  position  shown  in  fig.  452  and  fig.  453,  and  brings  the  port, 
K,  over  H. 

From  the  end  view,  fig.  447,  and  sectional  plan,  fig.  453  of  the  slide- 
valve,  6,  it  will  be  seen  that  one  corner  of  it,  at  Z,  is  cut  away  diagonally. 
Consequently  when  the  valve  reaches  the  position,  shown  in  figs.  452  and 
453,  it  uncovers  the  port, ,N.  Air  from  the  chamber,  C,  and  auxiliary 
reservoir  then  flows  down  through  the  passage,  N,  and  acts  on  the  piston, 
8,  fig.  446,  forcing  it  down,  which  opens  the  valve,  11.  As  soon 
as  this  occurs  the  pressure  in  the  chamber,  Q,  and  brake-pipe,  T,  below 
the  check-valve,  15,  raises  it,  and  there  is  then  a clear  passage  from  the 
brake-pipe,  T,  to  the  pipe,  S,  and  into  the  brake-cylinder.  There  is  also  a 
passage  from  the  auxiliary  reservoir  through  the  port,  K,  fig.  452,  and 
passages,  H and  /,  into  the . brake-cylinder,  but  as  the  area  of  the  cross 
sections  of  these  passages,  compared  with  that  through  the  valves,  11  and 
15,  is  relatively  small,  the  air  in  the  brake-pipe  has  time  to  discharge  into 
the  brake-cylinder  before  the  pressure  in  the  latter  has  been  increased 
much  by  that  which  enters  from  the  reservoir,  through  K and  I.  The 
air  in  the  brake-pipe  has  thus  time  to  discharge  into  the  cylinder  and 
thus  relieve  the  pressure  in  the  pipe  before  the  air  in  the  auxiliary 
reservoir  has  increased  the  pressure  above  the  check-valve,  15,  sufficiently 
to  close  it,  thus  preventing  the  air  above  it  from  flowing  back  into  the 
brake-pipe.  By  this  means  the  air  in  the  brake-pipe  under  each  vehicle 
is  discharged  into  the  brake-cylinder,  thus  utilizing  it  for  applying  the 
brakes  and  effecting  a quicker  discharge  of  air  from  the  brake-pipe  and 
more  prompt  application  of  the  brakes  than  is  possible  if  the  air  in  the 
brake-pipe  must  all  escape  through  the  engineer’s  valve. 

After  the  engineer  has  accomplished  his  object,  the  brakes  are  released 
in  the  usual  way,  by  opening  communication  between  the  main  reservoir 


Fig.  454.  Brake-Cylinder,  Auxiliary  Reservoir*  and  Triple- Valve. 


The  Westinghouse  Air-Brake. 


513 


and  the  brake-pipe  through  the  engineer’s  valve  on  the  engine.  The 
pressure  in  the  brake-pipe,  T,  fig.  446,  then  flows  through  the  passages, 
Q D D'  l /,  and  moves  the  piston,  5,  back  into  the  position  shown.  The 
cavity,  O,  in  the  valve  then  connects  the  passage,  A7,  with  the  atmosphere, 
which  relieves  the  pressure  above  the  piston,  8,  which  is  raised  by  the 
pressure  under  it,  and  the  valve,  11,  is  closed  by  the  spring,  12,  below  it. 
The  air  in  the  brake-cylinder  then  exhausts  through  the  passage,  /,  port, 
H,  cavity,  O,  in  the  valve  and  passage,  G,  into  the  open  air,  and  the 
springs  in  the  brake-cylinder  return  the  brake-pistons  and  take  off  the 
brake-blocks  from  the  wheels,  and  the  auxiliary  reservoirs  are  again  re- 
charged through  the  groove,  E. 

QUESTION  653.  How  is  the  quick  acting  triple-valve  applied  to  the 
brake-cylinders  ? 

Answer.  On  passenger  trains  it  is  attached  to  the  end  of  the  brake- 
cylinder,  as  shown  in  fig.  454,  which  is  a perspective  view  of  a brake- 
cylinder,  auxiliary  reservoir,  and  triple-valve — the  latter  shown  in  section 
— with  their  connections.  On  freight  trains  the  brake-cylinder  is  bolted 
to  the  end  of  the  auxiliary  reservoirs  and  the  triple-valve  is  bolted  to  the 
end  of  the  reservoir  with  a pipe,  a , running  through  the  latter,  for  convey- 
ing the  compressed  air  to  and  from  the  triple-valve  and  cylinder,  as  shown 
in  fig.  444,  which  represents  a section  of  these  parts.  A screw  plug,  26, 
fig.  446,  is  provided  in  the  bottom  of  the  air  chamber,  13,  for  removing 
any  dirt  which  may  accumulate  there. 

Question  654.  With  how  much  force  should  the  brake-blocks  be  pressed 
against  the  wheels  ? 

Answer.  The  friction  between  the  brake-blocks  and  the  wheels,  and 
between  the  wheels  and  the  rails,  or  the  “ adhesion  ” of  the  wheels,  is  very 
nearly  the  same  with  equal  pressures.  Therefore,  if  the  force  with  which 
the  brakes  are  pressed  against  any  of  the  wheels  should  be  greater  than 
the  weight  on  the  rails  under  those  wheels,  the  friction  of  the  brake-blocks 
would  exceed  the  adhesion  of  the  wheels  to  the  rails,  and  the  wheels  would 
slide.  For  this  reason  the  pressure  of  the  brakes  on  any  pair  of  wheels 
should  never  exceed  the  weight  on  the  rails  under  those  wheels.  Experi- 
ence has  shown  that  the  wheels  of  passenger  cars  are  liable  to  slide  if  the 
brake  pressure  on  any  of  the  wheels  exceeds  90  per  cent,  of  the  weight  on 
the  rails  under  them,  and  if  they  do  slide  they  are  liable  to  have  flat  spots 
worn  on  the  treads.  For  this  reason  the  pressure  of  the  brake  on  any 
wheel  of  a passenger  car  is  limited  to  90  per  cent,  of  the  weight  on  the 
rail  under  it  when  the  car  is  empty  or  light,  and  the  pressure  on  freight 


514 


Catechism  of  the  Locomotive. 


cars  is  limited  to  70  per  cent,  of  the  light  weight.  Practical  experience 
has  shown  that  75  per  cent,  of  the  weight  on  driving-wheels  can  be  safely 
used  as  a braking  force  without  harm  to  the  structural  parts  of  the  engine, 
but  it  is  not  advisable  in  any  case  to  have  a pressure  of  over  12,500  lbs.  on 
any  one  wheel,  because  a greater  pressure  causes  excessive  wear  of  tires. 


Arrangement  of  Brake-Levers. 


QUESTION  655.  How  is  the  pressure  applied  to  the  brake-shoes? 

Answer.  By  means  of  levers,  14  14'  14",  Plate  VI,  connected  to  the 
brake-beams  to  which  the  brake-shoes  are  attached. 

Question  656.  How  are  the  brake-levers  arranged  in  relation  to  the 
wheels  ? 

Answer.  The  levers  which  are  connected  to  the  brake-beams  are 
arranged  in  several  different  ways.  Fig.  455  shows  the  simplest  arrange- 


The  Westinghouse  Air-Brake. 


515 


ment  in  use  for  hand-brakes,  with  the  brake-blocks  or  shoes,  B B',  outside 
of  the  wheels.  It  consists  of  a single  lever,  a b c,  which  is  connected  to 
the  brake-beam,  e,  by  a fulcrum,  b.  The  lower  end,  c , of  the  lever  is  con- 
nected by  a rod,  c d,  to  the  brake-beam,  d.  The  upper  end,  a , of  the  lever 
is  connected  by  a rod,^*,  to  the  brake-windlass.  This  arrangement  is  open 
to  the  objection  that  the  pressure  on  the  brake-blocks,  B,  is  greater  than 
that  on  B',  and  therefore  this  plan  is  now  seldom  used. 

Fig.  456  represents  an  arrangement  with  double  levers  which  are  at- 
tached to  the  brake-beams  in  the  same  way  as  the  lever,  a b c,  shown  in 
fig.  455.  The  brake-blocks  are  also  outside  of  the  wheels,  and  the  lower 
ends  of  the  levers  are  connected  together  by  a rod,  c e.  The  upper  end  of 
the  lever,  e df,  is  held  by  an  adjustable  stop  at  f.  With  this  arrangement, 
the  rod,  c e , is  in  tension  when  the  brakes  are  applied  by  the  brake- 
windlass. 

Fig.  457  represents  an  arrangement  with  two  levers  and  the  brake-blocks, 
B B' , between  the  wheels.  The  upper  end,  d,  of  the  lever,  d b e,  is  con- 
nected to  the  brake-windlass,  and  f d e is  held  by  an  adjustable  stop,/". 
The  rod,  e e,  is  in  compression  when  the  brakes  are  applied. 

Fig.  458  shows  another  arrangement  similar  to  fig.  457,  excepting  that 
the  rod,  e e , is  above  instead  of  below  the  brake-beams. 

Question  657.  How  are  the  air-brake  cylinders  connected  to  the  brake- 
levers  ? 

Answer.  Two  systems,  the  Stevens  and  the  Hodge,  shown  by  figs.  459 
and  460,  are  used.  The  brake-cylinders  are  usually  placed  between  the 
two  trucks  and  have  two  levers,  g i and  g'  i' ; one  of  these,  g'  i' , is  con- 
nected to  the  brake-piston  at  i' , and  the  other,  g i,  to  the  brake-cylinder 
at  i.  They  are  connected  together  by  a tie-rod,  h h' , and  in  the  Hodge 
brake,  fig.  460,  by  rods,^  l and^-'  to  the  floating  levers,  k m and  k'  in'. 
In  the  Stevens  system,  fig.  459,  the  cylinder  levers  are  connected  directly 
to  the  brake-beam  levers,  a c and  a'  c'.  With  this  arrangement,  it  is  only 
necessary  to  give  the  levers  the  right  proportion  to  get  the  proper 
pressure  of  the  brakes  on  the  wheels. 

Question  658.  How  can  the  pressure  which  should  be  exerted  by  the 
brake-shoes  on  the  wheels  be  calculated? 

Answer.  The  first  thing  to  do  is  to  ascertain  the  minimum  weight  on 
the  rails  under  each  pair  of  wheels  of  the  car  or  other  vehicle  to  which  the 
brakes  are  applied.  This  is  done  by  taking  the  total  weight  of  the  car 
when  empty  and  dividing  it  by  the  number  of  its  pairs  of  wheels.  Then 
for  passenger  cars  take  90  per  cent,  and  in  the  case  of  freight  cars  70  per 


The  Westinghouse  Air-Brake. 


517 


cent,  of  the  weight  on  each  pair  of  wheels,  when  the  car  is  empty,  which 
will  be  the  pressure  which  should  be  exerted  on  each  brake-beam. 

Thus  suppose  we  have  an  eight-wheel  passenger  car  which  weighs  40,000 
lbs.  empty.  It  would  have  10,000  lbs.  of  weight  to  each  pair  of  wheels,  90 
per  cent,  of  which  would  be  9,000  lbs.,  which  is  the  pressure  that  should 
be  exerted  on  each  brake-beam. 

In  the  case  of  six-wheeled  trucks  on  which  the  brakes  are  not  usually 
applied  to  the  middle  pair  of  wheels,  the  calculation  is  made  in  the  same 
way,  the  only  difference  being  that  the  brakes  are  omitted  on  the  middle 
pair  of  wheels  if  the  brakes  are  not  applied  to  them. 

QUESTION  659.  What  should  be  the  pressure  in  the  brake-cylinders ? 

Answer.  Experience  has  shown  that  a pressure  of  50  lbs.  per  square 
inch  in  the  cylinders  of  the  old  automatic,  and  60  lbs.  with  the  new  quick- 
acting brake,  is  the  best  that  can  be  used.  The  size  of  the  cylinders  and 
the  brake-levers  should  then  be  so  proportioned  that  this  air  pressure  will 
exert  the  required  force  on  the  brake-beams. 

Question  660.  How  can  the  proportion  of  the  brake-levers  be  calcu- 
lated? 

Answer.  Their  proportions  are  calculated  from  the  principle  of  the 
lever  which  was  explained  in  Chapter  III. 

To  illustrate  how  this  can  be  done,  the  arrangement  of  lever  shown  in 
fig.  455  will  be  taken  first.  It  will  be  supposed  that  the  pressure  on  the 
brake-shoe  is  to  be  9,000  lbs.,  and  that  the  lower  end  of  the  lever  is  8, 
and  the  upper  one  24  inches  long;  what  force  must  be  exerted  at  a?  In 
this  case  the  pressure  on  the  brake-shoe  is  the  counter-force,  and  that  at 
a the  minor-force ; by  the  rule  given  in  answer  to  Question  48,  we  will 
have  9,000  x 8-^-32=2,250  lbs.=the  force  which  must  be  exerted  at  a.  To 
get  the  major-force  exerted  at  c,  on  the  rod,  c d,  and  brake-shoes,  B' , we 
have  by  the  rule  given  in  answer  to  Question  48,  9,000  x 24-^32=6,750. 
This  explains  what  has  already  been  pointed  out,  that  with  this  arrange- 
ment of  brakes  the  pressure  on  the  shoe,  B' , is  less  than  that  on  B. 

If  we  want  to  calculate  the  pressure  which  a force  at  a , of  2,250  lbs. 
would  exert  on  the  brake-shoe,  by  the  rule,  in  answer  to  Question  47,  we 
will  have  24  + 8=32  x 2,250 -^8 =9,000= pressure  on  B. 

The  calculations  are  similar  for  the  leverages  in  figs.  456,  457  and  458. 
In  fig.  456,  with  a force  of  2,250  lbs.  at  a , we  would  again  have  9,000  at  b, 
and  6,750  at  c,  and  as  this  is  exerted  on  the  rod,  c e , it  would  be  the  major- 
force  acting  on  the  lever,  f de.  To  get  the  pressure  exerted  on  the 
brake-shoe,  B',  by  the  rule  in  answer  to  Question  47,  we  would  have 


518 


Catechism  of  the  Locomotive. 


8 + 24  = 32  x 6,750  -4-  24  = 9,000  lbs.,  showing  that  with  this  arrangement 
of  levers  the  pressure  on  the  two  brake-shoes  is  equal. 

It  happens  in  applying  air-brakes  to  cars  that  the  proportions  of  the 
brake-beam  levers,  abc  and  f d e,  figs.  459  and  460,  are  nearly  always 
established  ; therefore  the  problem  usually  is  to  proportion  the  cylinder- 
levers,  g h i and  g'  ti  i',  to  produce  a given  pressure  on  the  brake-beams 
with  some  given  dimensions  of  brake-beam  levers. 

Question  661.  How  are  the  proportions  of  the  cylinder-levers  calcu- 
lated? 

Answer.  As  an  example,  we  will  take  the  dimensions  and  pressures 
referred  to  in  the  answer  to  the  previous  question,  and  represented  in  fig. 
456.  With  the  proportions  of  levers  given  to  exert  a force  of  9,000  lbs.  on 
the  brake-beams,  there  must  be  a pull  of  2,250  lbs,  on  the  rods,  a g and 
a' g\  fig.  459.  These  rods  are  connected  to  the  cylinder-levers,^  h i and 
g'  h’  i'.  One  of  these  levers  is  connected  to  the  cylinder  at  i,  and  the 
other  to  the  piston-rod  at  i',  and  they  are  connected  together  by  the  rod, 
h h' . Consequently,  when  the  piston-rod  is  forced  out  it  exerts  a pull  on 
the  rods,  h h' , g a and  g'  a' ',  which  is  communicated  to  the  levers,  abc 
and  a’  b'  c' . If  the  cylinder  is  10  inches  in  diameter — a usual  size  for 
passenger  cars — the  area  of  its  piston  will  be  78.5  square  inches,  which, 
multiplied  by  a pressure  of  50  lbs.  per  square  inch,  will  give  a total  pres- 
sure on  the  piston  of  3,925  lbs.,  which  for  even  figures  will  be  taken  at 
4,000  lbs.  The  total  length  of  the  cylinder-levers,  g h i and  g'  h'  i\  will 
be  assumed  to  be  30  inches,  and  it  has  been  shown  that  a pull  of  2,250  lbs. 
is  required  on  the  rods,  a g and^-'  a\  to  produce  the  required  pressure  on 
the  brake-beams.  The  problem,  then,  is  to  determine  the  length  of  the  two 
ends  of  the  cylinder-levers  so  that  a pressure  of  4,000  lbs.  exerted  by  the 
piston  at  i',  will  pull  with  a force  of  2,250  lbs.  at^  and^'.  We  have,  then, 
the  major  and  the  minor-forces  and  the  total  length  of  the  lever,  so  that 
by  the  rule  in  answer  to  Question  49,  we  would  have  2,250  + 4,000=6,250 
=the  counter-force  at  h and  h’ . 4,000  x 30^-6,250=19.2  inches=long  end 
of  lever.  The  length  of  the  short  end  of  the  lever  is,  of  course,  equal  to 
its  whole  length  less  the  length  of  the  long  end,  or  30  — 19.2=10.8  inches. 

Some  care  should  be  taken  not  to  get  the  position  of  the  ends  of  these 
levers  reversed  from  what  they  should  be.  The  short  end  should  always 
be  next  to  the  major-force  and  the  long  end  next  to  the  minor-force. 

Question  662.  What  different  arrangement  of  levers  is  used  in  apply- 
ing the  air-brake  ? 

Answer.  As  explained  in  answer  to  Question  657,  two  systems  are 


The  Westinghouse  Air-Brake. 


519 


commonly  used,  the  Stevens’,  fig.  459,  and  the  Hodge’s,  shown  in 
fig.  460.  In  the  latter,  what  are  called  floating-levers,  k l m and 
k'  l'  in',  are  used.  One  end,  m and  in',  of  each  of  these  levers  is 
connected  to  the  brake-beam  levers,  a b c and  a'  b'  c' , by  rods,  m 
a and  m!  a'  ; the  other  ends,  k and  k' , of  the  floating-levers  are  connected 
to  the  hand-brakes,  and  the  cylinder-levers,^  h i,g'  h'  i' , are  connected  to 
the  middle  of  the  floating-levers  by  rods,^  / and^'  /'.  It  is  obvious  that 
with  this  arrangement,  if  the  two  ends  of  the  floating-levers  are  of  equal 
length,  one-half  of  the  pull  which  is  exerted  by  the  cylinder-levers, 
through  the  rods,^  / and^-'  l' , is  transmitted  to  the  hand-brakes,  and  the 
other  half  to  the  levers,  a b c and  a ' b'  c.  Consequently,  with  this  arrange- 
ment the  cylinder-levers  must  be  so  proportioned  that  they  will  exert  a 
pull  through  the  rods,^  / and^-'  equal  to  double  that  which  must  act 
on  the  ends,  a and  a' , of  the  “live  ” brake-beam  levers,  a b c and  a'  b'  cf. 
In  this  case,  then,  the  levers  must  be  proportioned  so  that  for  the  con- 
ditions which  have  been  assumed,  a pressure  of  4,000  lbs.  on  the  piston  at 
i' , will  exert  a force  of  4,500  lbs.  at  g and  g' . The  calculation  for  the 
length  of  the  long  end  of  the  lever  would  therefore  be  4,500  + 4,000=8,500 
=the  counter-force  at  h and  h' . 4,500  x 30-4-8, 500=15|-=long  end  of  lever. 
It  will  be  noticed  that  in  figs.  459  and  460  the  relative  position  of  the  long 
and  short  ends  of  the  cylinder-levers  is  reversed  ; in  fig.  459  the  short  end 
is  next  to  the  cylinder,  whereas  in  fig.  460  the  long  end  is  in  that  position. 
The  force  exerted  on  the  rod,  h h' , fig.  460,  will  be  equal  to  the  counter-force, 
or  4,000  + 4,500=8,500  lbs.  By  calculating  the  effect  of  this,  it  will  be 
found  that  the  same  force  is  exerted  on  the  rods,  g l and  g'  l',  showing 
that  the  brakes  are  applied  equally  on  both  trucks. 

Question  663.  How  may  the  rules  for  calculating  the  length  of  brake- 
levers  be  summarized? 

Answer.  The  following  are  the  essential  rules  to  be  used  for  such 
calculations : 

I.  To  get  the  pressure  on  the  brake-piston:  Multiply  the  area  of 
THE  BRAKE-PISTON  IN  SQUARE  INCHES  BY  THE  AIR  PRESSURE  PER 
SQUARE  INCH,  IN  LBS.,  IN  THE  CYLINDER  (usually  50  lbs.). 

II.  To  get  the  pressure  on  each  brake-beam : For  PASSENGER  CARS 
TAKE  90  PER  CENT.  OF  THE  WEIGHT  (when  empty),  IN  LBS.,  ON  THE 
RAILS  BELOW  THE  WHEELS  TO  WHICH  THE  BRAKES  ARE  APPLIED  AND 
DIVIDE  BY  THE  NUMBER  OF  BRAKE-BEAMS. 

III.  To  get  the  force  which  must  be  exerted  at  the  upper  end  of  each 
brake-beam  lever  .-If  the  brake-beam  is  attached  to  the  lever  between  its 


520 


Catechism  of  the  Locomotive. 


two  ends  (as  in  figs.  456  and  457),  multiply  the  pressure  on  the  beam, 

IN  LBS.,  BY  THE  LENGTH  IN  INCHES  OF  THE  SHORT  END  OF  THE  LEVER,* 

and  divide  by  its  whole  length.  If  the  brake-beam  is  attached  to  the 
end  of  the  lever  (as  in  fig.  458),  multiply  the  pressure  on  it,  in  lbs., 
BY  THE  LENGTH  IN  INCHES  OF  THE  SHORT  END  OF  THE  LEVER,  AND 
DIVIDE  BY  THE  LENGTH  IN  INCHES  OF  THE  LONG  END. 

IV.  To  get  the  proportions  of  the  brake-cylinder  levers  : If  floating-levers 
are  not  used  (as  in  fig.  459) : Take  the  force,  in  lbs.,  exerted  at 
the  top  OF  each  live  brake-beam  lever  ; if  floating-levers  are  used 
(as  in  fig.  460,)  take  double  this  force  and  add  it  to  the  pressure, 

IN  POUNDS,  EXERTED  ON  THE  BRAKE-PISTON.  THEN  TO  GET  THE 
LENGTH  OF  THE  END  OF  THE  CYLINDER  LEVER  NEXT  TO  THE  CYLINDER, 
MULTIPLY  ITS  WHOLE  LENGTH  BY  THE  FORCE  EXERTED,  IN  LBS.-,  ON 
THE  OPPOSITE  END  OF  THE  LEVER,  AND  DIVIDE  THE  PRODUCT  BY  THE 
SUM  OF  THE  FORCES  EXERTED  AT  THE  TWO  ENDS  OF  THE  LEVER.  The 
length  of  the  other  end  of  the  lever  could  be  obtained  by  multiplying  its 
whole  length  by  the  pressure  exerted  on  the  piston  and  dividing  by  the 
sum  of  the  forces  as  before. 

Question  664.  In  what  distance  can  trains  be  stopped  at  different 
speeds  with  a quick-acting  automatic  brake  ? 

Answer.  This  to  some  extent  depends  upon  the  number  of  wheels  in 
the  train  to  which  the  brakes  are  applied.  If  all  the  wheels  in  a train, 
excepting  the  truck  wheels  of  the  locomotive,  have  brakes,  it  can  be 
stopped  quicker  than  is  possible  if  the  driving-wheels  have  no  brakes,  or 
if  the  cars  have  six-wheeled  trucks  on  which  brakes  are  seldom  applied  to 
the  middle  pair  of  wheels.  Under  the  most  favorable  conditions,  with  all 
the  cars  empty,  trains  can  be  stopped  in  about  the  following  distances : 


At  20  miles  an  hour 120  feet. 

“30  “ “ 270  “ 

“40  “ “ 480  “ 

“50  “ “ 750  “ 

“60  “ “ 1,080  “ 


If  the  cars  are  loaded,  these  distances  would  be  increased  in  the  propor- 
tion that  the  loads  bear  to  the  whole  weight  of  the  train. 

* The  length  of  a lever  should  always  be  measured  from  the  centres  of  the  pins  by  which  it 
is  connected  to  the  other  parts. 


CHAPTER  XXVII. 


THE  CARE  AND  USE  OF  THE  WESTINGHOUSE  AIR-BRAKE  * 

Question  665.  How  should  the  brake  gear  be  adjusted? 

Answer.  It  should  be  adjusted  so  that  when  the  brakes  are  full  on  the 
pistons  in  the  brake-cylinders  of  cars  will  not  have  travelled  less  than  7 
inches  nor  more  than  9 inches.  This  will  allow  for  wear  of  shoes,  stretch- 
ing of  rods,  springing  of  brake-beams,  etc.  Great  care  must  be  exercised, 
when  taking  up  the  slack  in  the  brake  connections,  to  have  the  levers  and 
pistons  pushed  back  to  their  proper  places,  and  the  slack  taken  up  by  the 
pins  and  holes  at  the  top  of  the  dead  levers  or  in  the  under  connections, 
23'  23",  Plate  VI,  of  the  levers. 

The  driving-wheel  brakes  should  be  adjusted  so  that  when  they  are 
fully  applied  the  piston  will  run  out  about  3 inches,  and  to  be  kept  ad- 
justed so  as  not  t.o  take  up  the  entire  stroke  of  the  pistons. 

Question  666.  Before  leaving  the  engine-house  what  should  the  en- 
gineer observe? 

Answer.  He  should  know  whether  the  engineer’s  brake-valve,  the  air- 
pump,  and  the  other  parts  of  the  brake  on  the  engine  and  tender  are  in 
perfect  working  order,  and  if  not  the  defects  should  be  promptly  reported. 

Question  667.  Before  coupling  to  a train  what  should  the  engineer  do? 

Answer.  He  should  know  that  the  steam-cylinder  of  the  air-pump  was 
properly  lubricated  with  locomotive  cylinder  oil,  and  that  the  air-cylinder 
is  sparingly  lubricated  with  a small  quantity  of  good  mineral  lubricating 
oil.  Tallow  and  lard  oils  should  not  be  used  in  the  air-cylinders. 

The  air-pump  should  be  started  slowly  to  allow  the  water  which  accu- 
mulates in  the  steam-cylinder,  from  the  condensation  of  the  steam,  to 
escape  gradually ; it  should  not  be  forced  out  by  running  the  pump  with 
full  steam  pressure.  After  the  pump  has  made  a few  strokes  put  about  a 
teaspoonful  of  West  Virginia  mineral  oil  into  the  oil-cup  of  the  air- 
cylinder. 

* In  the  answers  to  the  questions  in  this  chapter,  free  use  has  been  made  of  the  instruction 
book  by  the  Westinghouse  Air-Brake  Company,  and  of  other  similar  books  issued  by  some  of 
the  railroad  companies. 


522 


Catechism  of  the  Locomotive. 


Before  coupling  to  the  train,  the  main  reservoirs  should  be  pumped  ful\ 
of  air  of  the  maximum  pressure  of  90  lbs.,  to  insure  the  release  of  the 
brakes  on  the  train,  and  also  to  be  able  to  charge  the  auxiliary  reservoirs 
quickly  after  the  engine  is  coupled  to  the  train. 

After  being  connected  to  the  train  the  handle  of  the  engineer’s  valve 
should  be  turned  to  the  I,  or  “ charging  position,"  figs.  424  and  428,  until 
the  pressure  gauge  indicates  that  the  pressure  in  the  train-pipe  is  equal 
to  70  lbs.  The  handle  should  then  be  turned  to  the  II,  or  “ while  running 
position ,”  fig.  429,  in  order  to  accumulate  an  extra  pressure  of  20  lbs.  in  the 
main  reservoir. 

The  air-gauges  which  are  now  supplied  for  the  new  automatic  brake,  as 
already  explained,  have  two  sets  of  works  and  two  hands — a black  and  a 
red  one.  The  black  one  indicates  the  pressure  in  the  brake-pipe  and  the 
red  one  that  in  the  main  reservoir.  The  difference  of  pressure  indicated 
by  these  hands  represents  the  excess  of  pressure  which  is  accumulated  in 
the  main  reservoir  over  that  in  the  brake-pipe,  to  aid  in  releasing  the 
brakes  quickly  and  for  recharging  the  brake-pipe  and  auxiliary  reservoirs. 
This  excess  of  pressure  is  accumulated  when  the  handle  of  the  engineer’s 
valve  is  placed  in  the  II,  or  “ running  position,"  and  should  be  about  20 
to  25  lbs.  As  the  pressure  in  the  train-pipe  should  be  70  lbs.,  that  in  the 
main  reservoir  should  be  90- lbs.  The  importance  of  having  an  excess  of 
pressure  in  the  main  reservoir  cannot  be  emphasized  too  strongly. 

Question  668.  In  making  up  trains  what  should  be  done? 

Answer.  All  the  hose  couplings  between  the  different  vehicles  should 
be  connected  together  so  that  the  brakes  will  be  applied  throughout  the 
whole  train.  No  brake  in  any  car  must  be  “cut  out”  unless  it  is  defec- 
tive. The  coupling  of  the  hose  at  the  rear  of  the  last  car  and  at  the  front 
of  the  engine  (if  there  is  a hose  there)  should  be  attached  to  the  coupling- 
hook.  If  for  any  reason  the  hose  between  two  vehicles  are  not  used  for 
connecting  the  brakes  they  should  be  attached  to  their  coupling-hooks. 

In  coupling  the  hose,  place  the  coupling  shoulders,  near  the  stop-pin, 
firmly  together,  then  twist  the  heads  into  place  as  if  they  turned  on  a 
pivot,  firmly  pressing  the  heads  toward  each  other  until  both  heads 
strike  the  stop-pins. 

All  the  brake-pipe  cocks,  29'  29",  Plate  VI,  should  be  opened  by  turn- 
ing their  handles  down  or  at  right  angles  to  the  brake-pipe*  excepting  that 
of  the  cock  at  the  rear  end  of  the  train,  which  should  be  closed  by  turn- 

* On  the  old  brake  the  plugs  of  these  cocks  are  horizontal,  on  the  new  quick-acting  brake 
they  stand  vertical. 


Care  and  Use  of  the  Westinghouse  Air-Brake.  523 

ing  its  handle  so  as  to  stand  parallel  with  the  train-pipe.  If  the  brake- 
pipe  is  extended  to  the  front  of  the  engine,  to  connect  with  another 
engine,  the  cock  at  the  front  end  of  the  train  should  also  be  closed.  The 
hose  at  the  front  (if  there  is  one  at  the  front)  and  rear  ends  of  the  train 
should  be  attached  to  their  coupling-hooks. 

The  handles,  K,  fig.  422,  of  the  four-way  cocks  on  the  triple-valve  of  the 
old  brake,  and  the  handles  of  the  cocks  under  the  auxiliary  reservoirs 
should  also  be  turned  horizontal. 

The  new  or  quick  acting  triple-valve  has  no  four-way  cock  attached  to 
it,  but  has  a stop-cock,  A,  fig.  454,  on  the  pipe  which  connects  the  triple- 
valve with  the  brake-pipe.  This  stop-cock  should  be  opened  by  turning 
its  handle,  B,  at  right  angles  to  the  pipe  to  which  it  is  attached,  as  shown 
in  fig.  454.  When  the  cock  is  closed  the  handle  stands  horizontal.  This 
same  arrangement  is  used  on  the  new  freight  car  brakes. 

It  is  very  important  to  the  successful  action  of  the  brake,  and  to  avoid 
detentions,  that  the  handles  of  the  cocks  should  be  placed  in  their  proper 
position  before  starting. 

Question  669.  How  should  the  brakes  be  inspected  before  starting  ? 

Answer.  Before  leaving  terminal  stations,  or  wherever  there  has  been 
any  change  in  the  make-up  of  the  train,  after  all  the  couplings  are  made, 
the  engineer  should  turn  the  handle  of  the  engineer’s  valve,  9,  Plate  VI, 
to  the  I,  or  “ release  and  charging  position  ” (see  figs.  424  and  428),  and 
charge  the  auxiliary  reservoirs  with  air  of  not  exceeding  70  lbs.  pressure 
per  square  inch.  After  the  reservoirs  are  charged,  he  should  bring  the 
handle  to  the  III,  or  “ lap  position ,”  fig.  430,  leaving  it  in  this  position  for 
a few  moments  and  observing  whether  there  is  any  leakage,  which  will  be 
indicated  by  a gradual  falling  off  in  pressure,  as  shown  by  the  air-gauge. 
If  there  is  a leakage  it  should  be  found  and  the  defect  remedied.  The 
pipes  and  joints  of  the  brakes  must  be  kept  tight,  and  when  leaks  are 
discovered,  if  the  defect  is  a serious  one,  the  car  should  not  be  used  un- 
til it  is  repaired. 

A person  whose  duty  it  shall  be  to  inspect  the  brakes  and  know  that 
they  are  in  proper  order,  should  then  see  that  all  the  hand-brakes  are 
released,  and  then  ask  the  engineer  to  apply  the  brakes.  The  inspector 
should  then  walk  to  the  rear  of  the  train,  examining  the  brakes  of  each  car, 
and  see  whether  they  have  been  applied.  If  he  finds  them  set  all  right, 
he  should  signal  “off  brakes”  from  the  rear  of  the  train.  The  engineer 
should  reply  by  two  light  blasts  of  the  whistle  or  other  signal  and  imme- 
diately release  the  brakes.  The  inspector  should  then  return  to  the 


524 


Catechism  of  the  Locomotive. 


engine  and  notice  whether  the  brakes  are  released  on  every  car.  If  any 
are  found  which  are  still  set  he  should  release  them  by  opening  the  small 
cock,  20,  Plate  VI,  attached  to  the  under  side  of  the  auxiliary  reservoir  or 
cylinder,  which  is  called  “bleeding”  the  brake.  The  inspector  should 
then  observe  whether  there  is  the  full  air  pressure — 90  lbs. — in  the  main 
reservoir.  If  not  it  should  be  pumped  up  to  full  pressure  and  the  brakes 
applied  again  by  the  engineer.  If  those  which  were  not  released  on  to 
the  first  test  “stick”  again,  they  should  first  be  released  by  “bleeding” 
and  then  cut  out.  If  all  the  other  brakes  are  released,  the  brakemen  will 
report  all  right ; if  any  of  them  are  not  released,  they  should  be  cut  out  if 
they  do  not  release  on  the  second  trial.  After  the  inspection  it  should  be 
observed  that  all  the  cocks  in  the  auxiliary  reservoir  or  cylinder  are 
closed. 

It  should  be  understood  that  if  cars  which  have  different  air  press- 
ures in  the  brake-pipes  and  auxiliary  reservoirs  are  coupled  together,  air 
from  the  brake-pipe  having  the  higher  pressure  escapes  into  the  pipe  hav- 
ing the  lower  pressure,  and  thus  applies  the  brakes  on  the  car  which  has 
the  greatest  pressure.  In  such  cases  by  “bleeding”  the  cars,  with  over- 
pressure, until  the  brakes  commence  to  release,  the  time  required  to  equal- 
ize the  pressure  by  pumping  on  the  engine  will  be  saved. 

The  valves  for  the  application  of  the  brakes  from  the  inside  of  the  car 
should  also  be  examined  when  the  brakes  are  inspected,  and  it  should  be 
observed  whether  all  their  connections  are  tight  and  in  good  condition. 

The  discovery  of  a defect  in  the  brake  apparatus  affecting  its  working, 
either  before  or  during  a trip,  should  at  once  be  made  known  to  all  train- 
men and  to  the  engineer,  so  that  there  may  be  a proper  understanding  of 
it,  and  measures  should  be  taken  to  insure  safety  in  running  the  train. 

After  making  up  or  adding  to  a train,  or  after  a change  of  engines,  the 
rear  brakeman  should  ascertain  whether  the  brake  is  connected  through- 
out the  train.  The  engineer  must,  under  these  circumstances,  always  test 
the  brakes,  to  insure  their  being  properly  coupled  and  in  order  for  use. 

Question  670.  How  should  the  air-pump  be  worked? 

Answer.  While  the  locomotive  is  in  service  it  should  be  run  constantly, 
but  not  faster  than  is  necessary  to  maintain  the  required  air  pressure  in 
the  reservoirs.  The  pump  governor  being  connected  to  the  train-pipe 
should  constantly  be  used  and  should  be  set  to  maintain  a pressure  of  70 
lbs.  therein,  as  shown  by  the  air-pressure  gauge. 

While  running  the  handle  of  the  engineer’s  valve  should  be  kept  in  the 
II,  or  “ running  position ,”  figs.  424  and  429.  This  allows  the  brake-pipe 


Care  and  Use  of  the  Westinghouse  Air-Brake. 


525 


and  auxiliary  reservoirs  to  be  charged  with  air  and  an  excess  of  pressure 
to  be  accumulated  in  the  main  reservoir. 

Question  671.  How  should  the  brakes  be  applied  to  make  ordinary 
stops  ? 

Answer.  The  brakes,  as  has  been  explained,  are  applied  when  the  press- 
ure in  the  brake-pipe  is  suddently  reduced,  and  released  when  the  pressure 
is  restored. 

It  is  of  very  great  importance  that  every  engineer  should  bear  in  mind 
that  the  air  pressure  may  sometimes  reduce  slowly,  owing  to  the  steam 
pressure  getting  low,  or  from  the  stopping  of  the  pump,  or  from  a leakage 
in  some  of  the  pipes  when  one  or  more  cars  are  detached  for  switching 
purposes,  and  that  in  consequence  it  has  been  found  absolutely  necessary 
to  provide  each  cylinder  with  what  is  called  a leakage  groove,  which  per- 
mits a slight  pressure  to  escape  without  moving  the  piston,  thus  prevent- 
ing the  application  of  the  brakes  when  the  pressure  is  slowly  reduced,  as 
would  result  from  any  of  the  above  causes. 

This  provision  against  the  accidental  application  of  the  brakes  must  be 
taken  into  consideration,  or  else  it  will  sometimes  happen  that  all  of  the 
brakes  will  not  be  applied  when  such  is  the  intention,  simply  because  the 
air  has  been  discharged  so  slowly  from  the  brake-pipe  that  it  only 
represents  a considerable  leakage,  and  thus  allows  the  air  under  some 
cars  to  be  wasted. 

It  is  thus  very  essential  to  discharge  enough  air  in  the  first  instance, 
and  with  sufficient  rapidity,  to  cause  all  of  the  leakage  grooves  to  be 
closed,  which  will  remain  closed  until  the  brakes  have  been  released.  In 
no  case  should  the  reduction  in  the  brake-pipe  for  closing  the  leakage 
grooves  be  less  than  8 to  10  lbs.,  which  will  move  all  pistons  out  so  that 
the  brake-shoes  will  be  only  slightly  bearing  against  the  wheels.  After 
this  first  reduction  the  pressure  can  be  reduced  to  suit  the  circumstances. 

On  the  other  hand,  locomotive  runners  should  be  careful  not  to  use  too 
much  force  in  making  ordinary  stops.  By  applying  the  brakes  at  a fair 
distance  from  the  station,  with  moderate  force,  the  train  may  be  stopped 
gently  and  without  inconvenience  to  the  passengers,  while  if  the  brakes 
are  put  on  with  two  much  force,  the  train  is  jerked  in  a manner  that  is 
extremely  disagreeable,  and  may  be  dangerous  to  the  passengers.  To 
avoid  this  in  making  a stop,  the  handle  of  the  engineer’s  valve  should  not 
be  turned  beyond  the  IV  position ; “ for  service  stops”  see  figs.  424  and 
431.  With  a train  of  two  or  three  cars  the  handle  should  be  kept  in  that 
position  for  a few  seconds  only  and  should  then  be  closed  gently  by 


Catechism  of  the  Locomotive. 


526 

moving  the  handle  to  the  III  position,  when  the  pressure  in  the  brake- 
pipe  has  been  reduced  from  8 to  10  lbs.,  as  indicated  by  the  gauge.  The 
brakes  are  fully  applied  when  the  pressure  in  the  brake-pipe,  as  shown  by 
the  gauge,  has  been  reduced  about  20  lbs.  Any  further  reduction  is  a 
waste  of  air.  The  brakes  should  be  applied  far  enough  away  from  the 
station  so  that  the  train  may  be  controlled  and  stopped  without  moving 
the  handle  beyond  the  IV  position.  As  the  brakes  on  the  train  are 
applied  from  the  auxiliary  reservoirs,  frequent  use  of  the  brakes  reduces 
the  pressure,  and  consequently  the  power  of  the  brakes,  for  while  apply- 
ing the  brakes  the  supply  of  air  to  the  reservoirs  through  the  brake-pipe 
is  cut  off.  Therefore,  after  each  application  the  handle  of  the  engineer’s 
valve  should  be  turned  to  the  extreme  left  until  the  maximum  pressure  is 
obtained,  after  which  it  should  be  moved  to  the  II  position,  where  it 
should  remain  while  running.  It  is  bad  practice  to  apply  and  release  the 
brakes  more  than  once  or  twice  at  the  most  in  service  stops,  unless  time 
is  given  between  application  for  recharging  the  train  reservoirs,  as  it 
reduces  the  pressure  too  much  on  the  train. 

The  most  satisfactory  stops  are  made  by  applying  the  brakes,  lightly  at 
first,  at  sufficient  distance  away,  and  increasing  the  pressure  as  the  train 
draws  nearer  the  station  until  it  is  almost  stopped,  then,  excepting  on 
heavy  grades,  releasing  the  brake,  by  turning  the  handle  to  the  I position, 
to  avoid  jerking  the  train.  After  the  air  has  been  released  from  the  brake- 
pipe  of  long  trains,  by  placing  the  handle  of  the  brake-valve  in  the  IV,  or 
“ service  stop  ” position,  and  is  then  moved  back  to  the  III,  or  “ closed ” posi- 
tion, air  will  continue  to  escape  through  the  valve,  as  explained  in  answer 
to  Question  681,  until  the  pressure  has  been  reduced  uniformly  through- 
out the  brake-pipe  by  an  amount  indicated  by  the  black  pointer  of  the 
gauge.  This  is  the  equalizing  feature  of  this  valve  which  is  of  great  im- 
portance in  the  operation  of  the  brakes,  especially  on  long  trains. 

A reduction  of  pressure  in  train-pipe  of  about 

7 lbs.  will  give  about  4 lbs.  per  square  inch  in  brake-cylinder. 


9 “ 

“ 

“ 

“ 19  “ 

“ 

“ “ 

11  “ 

“ 

“ 

“ 26  “ 

“ 

it  a 

18  “ 

it 

“ 40  “ 

a a 

15  “ 

it 

it 

“ 46  “ 

17  " 

it 

it 

“ 50  “ 

“ 

Question  672.  How  should  the  air-brake  be  used  in  case  of  danger  ? 
Answer.  In  case  of  danger  the  object,  of  course,  is  to  stop  as  quickly 


Care  and  Use  of  the  Westinghouse  Air-Brake. 


527 


as  possible  without  reference  to  the  comfort  of  any  one.  In  such  cases 
the  handle  of  the  engineer’s  valve  should  be  turned  to  the  V,  or  “ emer- 
gency position,”  figs.  424  and  482.  Stops  should  not  be  made  in  this  way 
any  oftener  than  is  necessary,  as  they  are  liable  to  slide  and  flatten  wheels 
of  the  train. 

Question  673.  What  must  be  done  to  release  the  brakes? 

Answer.  The  handle  of  the  engineer’s  valve  must  be  turned  to  the 
extreme  left,  or  to  the  I,  or  “ release  position ,”  quite  against  the  stop,  and 
should  be  kept  there  until  the  brakes  are  fully  released  and  the  pressure 
in  the  train-pipe  is  restored,  and  then  moved  back  to  the  II  position 
against  the  intermediate  stop,  which  is  the  feed  position,  and  is  where  it 
should  remain  while  the  train  is  running.  This  course  is  necessary  so  as 
to  be  always  ready  with  an  excess  of  pressure  in  the  main  reservoir  to 
release  the  brakes,  thus  avoiding  the  necessity  of  “ bleeding.”  The  han- 
dle should  never  be  left  midway  between  these  two  positions,  as  this  will 
nearly,  if  not  quite,  close  the  passage  leading  to  the  brake-pipe. 

If  the  air-gauge,  while  running,  shows  too  much  excess  of  pressure,  the 
excess  pressure-valve,  21,  figs.  426  and  427,  may  have  become  obstructed. 
After  coming  to  a full  stop  at  a station,  move  the  valve-handle  to  the  V, 
or  “ emergency  position,”  and  accumulate  a high  pressure  in  the  main 
reservoir;  then  move  the  handle  back  from  the  V,  or  “ emergency  position,” 
to  the  II,  or  “ running  position ,”  so  that  the  full  reservoir  pressure  is 
brought  upon  the  excess  pressure-valve,  to  blow  out  any  obstruction.  If 
the  difficulty  is  thus  removed  the  black  hand  of  the  gauge  should  move 
up  to  within  20  lbs.  of  the  red  one ; if  it  does  not,  the  valve  should  be 
examined  and  cleaned. 

Where  two  or  more  engines  are  coupled  in  the  same  train,  the  cock,  8, 
fig.  B,  Plate  VI,  should  be  closed  upon  all  but  the  head  engine  of  the 
train,  in  order  to  permit  this  engine  to  handle  the  train-brakes  without 
interference  from  the  other  engines. 

Engineers  of  all  trains  should  avoid  making  exhibition  stops,  and  should 
never,  excepting  on  a heavy  grade,  or  in  case  of  necessity,  hold  the  brakes 
fully  applied  until  the  train  comes  to  a full  stop,  as  this  causes  a reaction 
in  the  motion  of  the  train  which  is  very  disagreeable  to  passengers,  and  in 
case  of  a long  freight  or  stock  train,  is  damaging  when  there  is  much  slack 
in  the  couplings.  This  can  be  avoided  ordinarily,  on  passenger  trains,  as 
already  explained,  by  releasing  the  brakes  gradually  before  coming  to  a 
full  stop,  so  that  all  the  air  will  be  off  at  the  moment  the  stop  is  made. 

On  long  down  grades  it  is  important  to  be  able  to  control  the  speed 


528 


Catechism  of  the  Locomotive. 


of  the  train,  and  at  the  same  time  to  maintain  good  working  pressure. 
This  is  easily  accomplished  by  running  the  pump  at  a good  speed,  so  that 
the  main  reservoir  will  accumulate  a high  pressure  while  the  brakes  are 
on.  When,  after  using  the  brakes  some  time,  the  pressure  has  been 
reduced  to  60  lbs.,  the  train-pipes  and  reservoirs  should  be  recharged  as 
much  as  possible  before  the  speed  has  increased  to  the  maximum  allowed. 
A greater  time  for  recharging  is  obtained  by  considerably  reducing  the 
speed  of  the  train  just  before  recharging  and  by  taking  advantage  of  the 
variation  of  the  grades. 

To  release  the  brakes  with  certainty,  it  is  important  to  have  a higher 
pressure  in  the  main  reservoir  than  in  the  main  pipe.  If  the  engineer 
feels  that  some  of  the  brakes  are  not  off,  it  is  best  to  turn  the  handle  of 
the  engineer’s  brake-valve  to  the  III,  or  “on  lap  position”  just  far  enough 
to  shut  off  the  main  reservoir,  and  then  pump  up  15  or  20  lbs.  extra,  which 
will  help  to  release  the  brakes,  all  of  which  can  be  done  while  the  train  is 
in  motion. 

Question  674.  If,  while  the  train  is  moving,  the  brakes  are  applied 
from  some  cause  unknown  to  the  engineer,  what  should  he  do  ? 

Answer.  Whenever  the  brakes  are  applied  from  any  cause,  it  is  impor- 
tant to  maintain  an  excess  of  pressure  in  the  main  reservoir,  in  order  to 
be  able  to  release  them  promptly  thereafter.  If  there  is  but  a slight 
reduction  of  pressure  in  the  train-pipes,  indicating  that  the  brakes  have 
been  applied  by  leakage,  he  should  at  once  move  the  handle  of  the  brake- 
valve  to  the  I position  in  order  to  release  them  ; but  if  the  brakes  should 
be  applied  at  once  and  the  air-gauge  show  that  all  the  air  in  the  train-pipe 
has  escaped,  he  will  know  that  a pipe  or  hose  has  burst,  a coupling  has 
been  broken,  or  that  a conductor’s  valve  has  been  opened,  and  he  should 
aid  in  stopping  the  train  by  turning  the  handle  to  the  V,  or  “emergency 
position,"  to  stop  as  quickly  as  possible,  and  also  to  prevent  the  escape  of 
air  from  the  main  reservoir.  When  the  train  is  stopped  he  can  release 
the  brakes  and  await  the  signal  from  the  conductor  to  proceed.  If  the 
brakes  are  not  released  by  turning  the  handle  to  the  I,  or  “ release  ” posi- 
tion, it  should  put  on  the  III,  or  “ closed ” position,  until  the  pressure  in  the 
main  reservoir  has  been  increased  10  or  15  lbs.,  and  the  handle  should 
then  be  turned  to  the  I,  or  “release"  position.  If  this  does  not  accom- 
plish the  desired  end,  the  brakes  should  be  applied  quickly  and  then 
released.  If  the  engineer  is  not  able  to  release  the  brakes,  he  should 
signal  the  fact  to  the  trainmen,  who  will  then  assist  in  releasing  them  by 
“bleeding.” 


Care  and  Use  of  the  Westinghouse  Air-Brake. 


529 


Question  675.  How  are  the  brakes  applied  from  the  inside  of  the  cars? 

Answer.  This  can  be  done  in  three  different  ways  : First,  by  opening 
the  conductor’s  valve,  by  pulling  on  its  cord  and  holding  it  down  until  the 
train  is  stopped.  The  new  form  of  conductor’s  valve  has  no  spring,  and 
is  open  when  the  handle  is  up,  and  will  remain  so  without  holding  it ; 
second,  by  disconnecting  the  hose  couplings;  third,  by  opening  the 
cock,  29",  Plate  VI,  on  the  brake-pipe  on  the  rear  end  of  the  train.  These 
methods  should  be  used  only  in  cases  of  emergency. 

Question  676.  In  running  trains  up  or  down  steep  grades  exceeding 
ioo  feet  per  mile  and  a half  mile  in  length,  what  shoidd  be  observed? 

Answer.  The  engineer  should  first  assure  himself  that  the  brake 
apparatus  is  in  good  working  condition.  Before  going  down  such  grades 
he  should  examine  the  valve-gear  of  the  locomotive  carefully,  to  see  that 
it  will  be  efficient  if  the  engine  is  reversed. 

Question  677.  Why  is  the  train-pipe  carried  to  the  front  end  of  the 
locomotive  ? 

Answer.  This  is  done  so  that  the  brakes  on  the  locomotives  can  be 
coupled  together,  in  case  two  are  used  on  the  front  of  the  same  train 
— called  a “double  header” — or  so  that  the  brakes  can  be  coupled  to  the 
rear  car  in  case  the  locomotive  is  used  as  a pusher  at  the  back  end  of  a 
train. 

Question  678.  How  are  the  air-brakes  operated  on  a “ double  header,” 
or  when  two  engines  are  coupled  together  ? 

Answer.  When  two  or  more  engines  equipped  with  air-brakes  are 
coupled  to  a train,  the  forward  engine  should  control  the  air-brake,  but  all 
the  engines  should  be  connected  to  the  brake-pipe.  When  the  train  is  in 
motion,  the  stop-cock,  8,  fig.  B,  Plate  VI,  should  be  closed  upon  all  but 
the  leading  engine,  and  the  leading  engineer  should  do  all  the  braking. 
Otherwise  the  brakes  may  all  be  pumped  off,  by  the  rear  engineer,  very 
soon  after  the  brakes  are  applied  by  the  first  engineer,  and  this  will  ren- 
der the  brakes  useless.  Hence,  the  leading  engine  must  control  the  train 
brakes  entirely  and  absolutely,  except  in  case  of  accident  to  the  air  of 
leading  engine,  and  until  a proper  signal  is  given  by  the  first  engineer  for 
the  second  engineer  to  assume  control  of  the  air-brakes  on  the  train,  for 
which  contingency  the  second  engineer  must  at  every  moment  be  pre- 
pared to  act  instantly  on  a mountain  grade. 

If  from  any  cause  the  supply  of  air  or  any  part  of  the  brake  on  the  lead- 
ing engine  has  failed,  and  it  is  desired  to  give  up  the  control  of  the  brakes 
to  the  second  engineer,  a signal  (usually  two  short  and  one  long  blast  of 


530 


Catechism  of  the  Locomotive. 


the  whistle ) should  be  given  by  the  first  engineer,  and  the 

second  one  by  repeating  it  should  signify  that  he  understands  it  and  has 
control  of  the  air-brakes.  The  second  engineer  having  assumed  control  of 
the  brakes,  should  retain  entire  charge  of  them  to  the  end  of  the  trip,  un- 
less it  may  be  necessary  to  again  put  them  in  charge  of  the  first  one.  On 
heavy  grades  the  aim  of  the  engineer  should  always  be  to  keep  control  of 
the  train.  Descending  at  high  speed  must  not  be  practiced  with  any  train , 
for  there  may  come  a time  when  some  part  of  the  machinery  may  fail,  and 
while  it  may  be  practicable  to  co7itrol  speed  by  hand-brakes  at  8 to  10  miles 
per  hour , it  may  be  impossible  at  20  to  30  miles  per  hour  to  regain  its  control* 

The  driver  brakes  should  not  be  used  too  freely  on  mountain  grades, 
as  it  heats  the  tires  of  driving-wheels,  expands  and  may  loosen  them  on 
the  wheel  centres,  and  thus  not  only  destroy  their  brake  efficiency,  but 
may  make  the  engine  useless  for  draft  purposes  also. 

Question  679.  How  can  the  brakes  be  released  if  they  are  applied  on  a 
car  which  is  not  coupled  to  an  engine , or  if  from  other  cause  they  cannot  be 
released  by  the  locomotive  runner  ? 

Answer.  On  passenger  cars  this  is  done  by  turning  down  the  handle 
of  the  release  cock,  20,  Plate  VI — below  the  auxiliary  reservoir — which 
opens  it  and  allows  the  air  in  the  reservoir  to  escape  ; which — in  railroad 
parlance — “ bleeds  ” the  reservoir  and  the  brake-cylinder. 

Question  680.  How  can  the  brakes  be  released  when  they  have  been 
applied  by  a burst  hose  ? 

Answer.  By  closing  the  brake-pipe  cock  directly  in  front  of  the  burst 
hose ; the  brakes  ahead  of  it  can  then  be  released  by  the  locomotive  run- 
ner, and  those  behind  it,  as  has  been  described  in  answer  to  the  previous 
question. 

Question  681.  What  is  meant  by  “ cutting  out  ” the  brakes  on  a car  ? 

Answer.  It  means  that  the  compressed  air  in  the  brake-pipe  is  shut  off 
from  the  triple-valve,  auxiliary  reservoir,  and  brake  cylinder,  so  that  they 
do  not  operate,  but  the  air  can  still  pass  through  the  brake-pipe  to  the 
cars  behind. 

Question  682.  How  can  the  brakes  on  a car  be  cut  out  ? 

Answer.  With  the  old  form  of  automatic  brake,  the  handle,  K,  fig. 

422,  of  the  four-way  cock  attached  to  the  triple-valve  should  be  turned 

down  to  the  half-way  position,  K,"  and  the  release  cock  below  the  auxiliary 

reservoir,  should  be  opened.  When  the  quick-acting  triple-valve  is  used, 
. % 

* From  the  Code  of  Rules  Governing  Engineers  and  other  Employees  in  the  use  of  the  West- 
inghouse  Air-Brakes  on  the  Northern  Pacific  Railroad. 


Care  and  Use  of  the  Westinghouse  Air-Brake. 


531 


the  handle,  B,  of  the  cock  shown  in  fig.  454  should  be  turned  to  the  hori- 
zontal position  to  cut  out  the  brakes  on  that  car. 

QUESTION  683.  What  must  be  done  if  a car  or  the  engine  is  detached 
from  the  train  f 

Answer.  When  any  of  the  vehicles  in  a train  must  be  uncoupled,  train- 
men should  not  close  the  brake-pipe  cocks,  by  turning  their  handles  at 
right  angles  to  the  brake-pipe,  or  disconnect  the  hose  until  the  brakes 
have  first  been  released  by  the  engineer.  Before  engines  or  cars  are  un- 
coupled, the  brakes  should  be  fully  released  on  the  whole  train.  Neglect- 
ing this  precaution,  or  setting  the  brakes  by  opening  a valve  or  cock  when 
the  engine  is  detached,  may  cause  serious  inconvenience  in  switching. 

The  cocks,  29'  29",  Plate  VI,  before  and  behind  the  hose  couplings  to  be 
separated  should  then  be  closed — by  turning  their  handles  at  right  angles 
to  the  brake-pipe — to  prevent  the  application  of  the  brakes  on  the  cars 
which  are  uncoupled.  The  hose  couplings  should  then  be  disconnected. 
This  must  always  be  done  by  hand , and  the  couplings  should  then  be  hung 
on  their  coupling-hooks. 

QUESTION  684.  What  is  essential  in  taking  care  of  the  brake-cylinders 
and  other  parts  of  the  brakes  ? 

Answer.  The  brake-cylinders  must  always  be  kept  clean  and  free  from 
gum,  so  that  they  will  readily  release  when  the  air  has  been  discharged, 
and  should  be  oiled  once  in  three  months  with  suitable  oil  furnished  for 
that  purpose.  The  last  date  of  oiling  should  be  marked  on  the  cylinders 
with  chalk.  The  pistons  should  be  taken  out  once  a year  and  cleaned,  at 
which  time  the  brake  rigging  should  have  a general  overhauling  and  be 
tested.  The  date  of  this  general  overhauling  and  testing  should  be  sten- 
cilled in  white  lead  on  the  cylinder. 

All  parts  of  the  brakes  should  be  kept  clean  and  in  good  condition,  and 
the  pipe  connections  tight. 

Question  685.  How  should  the  air-pumps  be  taken  care  of  ? 

Answer.  The  steam-cylinder  should  be  lubricated  with  a small  quan- 
tity of  engine  oil,  and'the  air-cylinder  should  be  sparingly  lubricated  with 
a small  quantity  of  32°  gravity  West  Virginia  mineral  oil  (tallow  or  lard 
oil  should  not  be  used  in  the  air-cylinder). 

In  case  the  air-pump  gets  hot  in  operation  on  the  road,  use  a small 
amount  of  valve  oil,  not  tallow,  to  overcome  the  difficulty  temporarily. 
Head-light  oils  will  cut  the  gum  out,  but  except  it  is  very  thoroughly 
cleaned  out  will  cause  heating  worse  than  before,  and  is  bad  oil  to  use  on 
this  account. 


532 


Catechism  of  the  Locomotive. 


The  best  means  for  cleaning  out  the  air-pump  thoroughly,  and  it  should 
be  done  at  the  shops,  is  to  disconnect  the  discharge  pipe  and  pump 
through  a few  quarts  of  weak  lye,  discharging  it  into  a proper  vessel  and 
pumping  it  through  again  until  all  passages  are  thoroughly  cleaned. 
After  the  lye  use  clean  warm  water,  to  thoroughly  clean  out  all  the  pass- 
ages, then  remove  the  lower  head,  shove  the  piston  to  the  upper  head, 
and  oil  the  cylinder  bore  with  oily  waste. 

Question  686.  How  should  the  triple-valves  be  taken  care  of? 

Answer.  In  cold  or  damp  weather  they  should  be  drained  frequently 
to  let  out  any  water  that  may  have  collected.  This  can  be  done  by  slack- 
ing the  nut  or  the  plug  in  the  bottom  of  the  triple-valve,  and  thus  letting 
the  water  escape  ; the  plug  should  then  be  screwed  up  again.  The  water 
in  the  drain-cup  on  the  tender  should  be  drained  out  daily  in  cold  or 
damp  weather  by  the  cock  under  it.  The  valves  for  the  application  of 
the  brakes  from  the  inside  of  the  car  should  be  kept  tight. 

Question  687.  What  should  be  observed  with  reference  to  the  main 
reservoir  ? 

Answer.  The  water  should  be  drained  out  of  it  ordinarily  once  a week, 
and  in  winter  or  damp  weather  daily.  If  the  pump  is  not  kept  well  packed 
considerable  water  will  accumulate  in  the  main  reservoir. 

Question  688.  What  should  be  done  in  case  a train  breaks  in  two? 

Answer.  In  case  a train  breaks  in  two,  the  brakeman  should  close  the 
stop-cock  on  the  rear  car  of  the  part  of  the  train  remaining  attached  to  the 
engine,  when  he  reaches  it,  and  then  give  the  engineer  a signal  to  let  the 
brakes  off. 

When  cars  are  again  properly  coupled  up,  before  opening  the  air  into 
the  rear  end  of  the  train , the  brakeman  should  give  the  engineer  a signal 
to  set  the  brakes,  which  should  be  done  strong,  and  be  left  on  until  the 
brakeman  opens  the  air-cocks  into  the  rear  section  of  the  train.  When 
this  is  done  the  engineer  will  have  regained  the  same  control  of  the  air 
in  the  entire  train  as  he  had  before  the  break  in  two.  This  action  will 
save  valuable  time,  which  otherwise  may  be  spent  in  releasing  the  air 
on  each  car  by  hand. 

Question  689.  What  should  be  done  in  case  hose  couplings  are  frozen , 
so  that  they  cannot  be  uncoupled , or  leak? 

Answer.  They  should  be  thawed  with  a lighted  torch,  care  being  taken 
not  to  heat  them  so  hot  as  to  injure  the  packing  or  rubber  of  which  the 
hose  is  made. 

QUESTION  690,  How  does  the  automatic  freight  train  brake  operate? 


Care  and  Use  of  the  Westinghouse  Air-Brake. 


538 


Answer.  The  construction  and  operation  of  the  freight  train  brake  is 
substantially  the  same  as  that  of  the  passenger  train  brake.  The  parts  of 
the  freight  brake  are,  however,  lighter  and  are  arranged  more  compactly. 
They  are  shown  in  figs.  440-445. 

Question  691.  When  and  how  is  the  pressure-retaining  valve  used  on 
freight  cars? 

Answer.  As  explained  in  answer  to  Question  649.  In  going  down  long 
grades  it  becomes  necessary  for  the  engineer  to  recharge  the  reservoirs 
with  air,  and  to  do  so  he  is  obliged  to  release  the  brakes.  When  the 
handle  of  the  pressure-retaining  valvei  40,  fig.  440,  which  is  located  at  the 
end  of  the  car  near  the  brake-wheel,  is  turned  horizontal,  as  shown  in  fig. 
445,  an  air  pressure  of  15  lbs.  is  retained  in  the  brake-cylinder  after  the 
brake  is  released  by  the  engineer.  When  the  valve-handle  points  down, 
the  valve  allows  the  air  to  exhaust  freely  from  the  brake-cylinder  when 
the  brakes  are  released.  The  retaining  feature  of  this  valve  should  only 
be  used  on  long  grades;  at  all  other  times  the  valve-handles  should  be 
turned  to  point  down. 

Question  692.  What  precaution  should  be  taken  in  cases  when  only  a 
part  of  the  cars,  or  the  engine  and  tender  only  are  equipped  with  air-brakes? 

Answer.  After  shutting  off  steam  from  the  engine,  engineers  should 
allow  the  slack  of  the  train  to  close  in  against  the  engine  before  applying 
the  brakes.  This,  to  a great  extent,  will  prevent  concussions  of  cars 
against  each  other  in  the  rear. portion  of  the  train,  which  are  not  provided 
with  air-brakes. 


CHAPTER  XXVIII. 


THE  EAMES  VACUUM  DRIVING-WHEEL  BRAKE. 

Question  693.  What  difference  is  there  in  the  principle  of  working  of 
vacuum  and  air-brakes? 

Answer.  In  air-brakes  the  force  which  applies  the  brakes  is  exerted 
by  air  of  a pressure  considerably  greater  than  that  of  the  atmosphere, 
whereas  in  vacuum  brakes  the  force  is  exerted  by  ordinary  atmospheric 
pressure. 

Question  694.  By  what  means  is  the  atmospheric  pressure  exerted  to 
apply  the  brakes  ? 

Answer.  The  air  is  exhausted  from  a cylinder  or  other  vessel,  so  that 
the  pressure  of  the  atmosphere  acts  on  the  opposite  side  of  a piston  or 
diaphragm,  and  thus  exerts  the  requisite  force  to  apply  the  brakes. 

Question  695.  How  is  the  air  exhausted? 

Answer.  Usually  by  means  of  an  instrument  called  an  “ejector.” 

Question  696.  How  is  an  ejector  constructed  and  how  does  it 
operate  ? 

Answer.  It  consists  of  a tube,  A,  fig.  461,  to  which  a current  of  steam 
is  admitted  by  the  pipe,  B.  As  indicated  by  the  darts,  the  steam  enters 
the  tube  through  the  annular  space  around  the  internal  nozzle,  D.  This 
produces  what  is  called  an  “ induced  current  ” of  air  through  the  tube,  D, 
or,  in  other  words,  the  steam  escaping  into  A , draws  the  air  in  D after  it, 
and  thus  produces  a partial  vacuum  above  the  valve,  E,  the  air  pressure 
below  raises  the  valve,  the  air  is  then  exhausted  from  the  space,  F,  below 
it  from  the  pipe,  G,  and  from  a diaphragm  vessel,  with  which  the  pipe,  G, 
is  connected. 

Question  697.  How  is  the  diaphragm  arranged  and  how  does  it 
operate  ? 

Answer.  Fig.  463  represents  the  diaphragm  vessel,  H,  the  lower  portion 
being  shown  in  section.  It  has  a wide  open  mouth,  with  a flange,  b b, 
around  it.  This  open  mouth  is  covered  by  an  india-rubber  diaphragm,  d 
d,  which  is  attached  to  the  flange,  b b,  by  a ring  below  it  and  bolts  shown 
in  the  engraving.  The  diaphragm  has  two  metal  plates,  e and  f , in  the 


Fig.  461. 

Ejector  and  Arrangements  for  Eames’  Vacuum  Brake.  Scale  2 in.— 1 ft. 


536 


Catechism  of  the  Locomotive. 


middle,  with  a bolt  and  eye,  g,  fastened  to  them  by  a nut,  which  holds  the 
plates  and  diaphragm  together. 

Question  698.  How  do  the  ejector  and  diaphragm  operate  to  apply  the 
brakes  ? 

Answer.  The  ejector  is  placed  in  any  convenient  position  on  the  engine 
— usually  on  the  side  of  the  fire-box,  as  shown  at  E,  fig.  464.  The  pipe, 
G G,  of  the  ejector  is  connected  to  the  diaphragm  vessel,  H,  and  the  eye, 
g,  on  the  diaphragm  is  connected  by  a rod,^  h,  to  the  arm,  h i,  which  is 
attached  to  a shaft,  i.  This  shaft  has  a short  arm,  //,  which  is  connected 
to  the  brake-shoes  by  a rod.  k.  L is  the  vacuum-lever  located  inside  of  the 
cab,  and  shown  on  an  enlarged  scale  in  fig.  461.  Steam  is  admitted  to 
the  ejector  by  a valve,  v,  fig.  462,  which  is  attached  to  the  stem,  /.  This 
valve  is  operated  by  means  of  the  vacuum-lever,  Z,  fig.  461,  which  is  con- 
nected by  a rod,  R,  to  an  arm,  I J,  shown  by  dotted  lines  in  fig.  461.  This 
arm  is  attached  to  a shaft,  J , fig.  462,  which  has  a short  arm  or  toe,  K , 
connected  to  it.  When  the  lever,  Z,  is  moved  backward  or  toward  the 
left-hand  side  of  the  engraving,  the  toe,  K,  lifts  the  spindle,  /,  and  valve, 
v,  fig.  462,  which  admits  steam  to  the  annular  space  around  D in  the 


Fig.  463.  Diaphragm  Vessel  for  Vacuum-Brake. 


ejector,  and  its  escape  produces  a partial  vacuum  in  the  pipe,  G,  and 
diaphragm  vessel,  H,  fig.  464,  as  has  been  explained.  When  this  occurs 
the  air  below  the  india-rubber  diaphragm  presses  it  upward,  and  this 
pressure  is  communicated  to  the  brake-shoes  through  the  connections, 
g h ij  and  k,  fig.  464.  When  the  brakes  have  been  applied  sufficiently, 
the  lever,  Z,  fig,  461,  is  moved  forward,  or  td&ard  the  right  in  the  engrav- 
ing, to  the  middle  position  in  which  it  is  shown.  This  lowers  the  toe,  K , 
and  allows  the  steam-valve,  v,  to  close.  When  the  current  of  steam  is 
shut  off  the  air  flows  into  the  pipe,  A , and  nozzle,  D,  and  its  pressure  on 


1 


/ 

— 

fill 

; 

\g  i 

Fig.  464.  Eames’  Vacuum  Driving-Wheel  Brake. 


538 


Catechism  of  the  Locomotive. 


top  of  the  check-valve,  E,  closes  it,  and  retains  the  vacuum  in  the  pipe,  G , 
and  diaphragm  vessel,  H. 

Question  699.  How  is  the  brake  released ? 

Answer.  The  lever,  L , is  moved  still  farther  forward,  or  toward  the 
right  hand  side  of  the  engraving,  from  the  position  in  which  it  is  shown 
in  fig.  461.  This  moves  the  shaft,  J,  which  has  an  arm,  m , that  engages 
with  a pin,  n,  attached  to  a release-valve,  o,  and  this  action  opens  the 
valve.  The  air  then  flows  into  the  ejector,  E,  pipe,  G,  and  diaphragm 
vessel,  H,  fig.  464,  and  equalizes  the  pressure  above  and  below  the  dia- 
phragm and  releases  the  brakes.  The  release-valve,  o,  has  a spring,  s,  on 
its  spindle,  to  close  it  when  the  lever,  Z,  is  moved  back  to  the  position 
shown  in  fig.  461. 

M is  a pressure  gauge  to  show  how  much  the  pressure  has  been  reduced 
in  the  ejector. 

Question  700.  How  much  pressure  can  be  exerted  on  the  brakes  by  the 
ejector  and  diaphragm  ? 

Answer.  This  depends  upon  the  size  and  number  of  the  diaphragms. 
The  manufacturers  of  this  brake  recommend  that  for  driving-wheels — for 
which  purpose  it  is  chiefly  used — that  a pressure  upon  the  brake-shoes 
equal  to  about  65  per  cent,  of  the  weight  on  the  wheels  should  be 
employed. 

QUESTION  701.  How  is  the  pressure  on  the  brake-shoes  of  the  different 
wheels  equalized? 

Answer.  The  rod,  k , fig.  464,  is  connected  to  a circular  disc,  E,  fig.  465, 


Pig.  465.  Brake-Shoe  for  Eames’  Brake. 


which  has  two  shafts  or  spindles,  s and  T,  which  are  located  eccentrically 
or  on  each  side  of  the  true  centre  of  the  disc.  When  a strain  of  tension 


The  Eames  Vacuum  Driving-Wheel  Brake. 


539 


is  exerted  on  the  rod,  k , it  draws  the  brake-shoe,  B,  against  the  wheel,  C, 
but  at  the  same  time  it  exerts  a tension  on  the  rod,  /,  which  is  communi- 
cated to  the  shoe  on  the  next  wheel,  and  to  as  many  more  as  have  the 
brakes  applied  to  them. 

Question  702.  For  what  service  is  the  vacuum-brake  most  used? 

Answer.  It  is  now  applied  chiefly  to  the  driving-wheels  of  locomotives, 
but  is  also  used  on  short  trains  which  make  frequent  stops,  as  on  the 
elevated  railroads  of  New  York. 


CHAPTER  XXIX. 


PROPORTIONS  OF  LOCOMOTIVES. 

QUESTION  703.  In  proportioning  a locomotive  to  any  given  kind  of 
work , what  are  the  first  facts  which  should  be  known  ? 

Answer.  We  should  first  know  the  weight  of  the  train  which  the  loco- 
motive must  draw;  second,  the  speed  at  which  it  must  run;  and  third, 
the  steepest  grades  and  the  shortest  curves  of  the  road  on  which  it  must 
work.  From  these  data  the  resistance  of  the  train  which  the  locomotive 
must  overcome  can  be  at  least  approximately  determined. 

Question  704.  When  the  greatest  resistance  of  a train  is  known,  what 
is  the  next  thing  to  be  determined? 

Answer.  As  was  stated  in  answer  to  Question  178,  if  the  wheels  revolve 
and  their  adhesion  is  greater  than  the  resistance  opposed  to  the  move- 
ment of  the  locomotive,  the  latter  will  overcome  the  resistance ; but  if  the 
latter  is  greater  than  the  friction,  the  wheels  will  slip.  It  therefore  follows 
that  the  adhesion  must  be  somewhat  greater  than  the  resistance.  As  the 
adhesion  is  equal  to  about  one-fifth*  of  the  adhesive  weight  or  pressure 
of  the  driving-wheels  on  the  rails,  obviously  this  weight  should  be  five 
times  the  resistance.  Thus,  if  we  have  a train  weighing  400  tons  which 
we  want  to  take  up  a grade  of  40  feet  per  mile  at  a speed  of  20  miles  per 
hour,  its  resistance,  calculated  from  the  table  given  in  Chapter  XXXI, 
would  be  9,360  lbs.  Therefore,  9,360x5=46,800  lbs.=the  required  ad- 
hesive weight. 

Question  705.  What  considerations  determine  the  manner  of  distribu- 
ting this  weight  on  the  wheels  ? 

Answer.  It  is  found  by  experience  that  if  too  much  weight  is  placed 
upon  one  wheel,  the  material  of  which  the  rails  are  made  is  partly  crushed 
and  injured,  and  they  then  wear  out  much  more  rapidly  than  they  would 
if  the  weight  was  distributed  on  more  wheels,  and  thus  a smaller  amount 
of  weight  rested  on  each  point  of  contact  with  the  rails.  The  amount  of 
weight  which  can  be  carried  on  a single  wheel  depends  upon  the  material 


* See  answer  to  Question  444. 


Proportions  of  Locomotives. 


541 


of  which  the  rails  are  made,  and  to  some  extent  on  their  form  and  size,  or 
as  the  latter  is  usually  expressed,  on  their  weight  per  yard. 

Question  706.  When  the  adhesive  weight  and  the  number  of  driving- 
wheels  are  known,  how  is  the  size  of  the  latter  determined  ? 

Answer.  The  size  of  the  wheels  will,  to  a certain  extent,  depend  upon  the 
speed,  because  the  larger  the  wheels,  the  further  will  the  locomotive  move 
in  one  revolution ; but  no  exact  rule  can  be  given  for  their  size.  At 
present  there  is  still  a great  diversity  of  opinion  among  engineers  regard- 
ing the  best  sizes  of  wheels  for  any  given  service.  Probably  the  safest 
plan  will  be  to  consult  the  best  practice,  and  in  the  absence  of  any  better 
reasons  be  guided  by  that. 

Question  707.  What  requirement  determines  the  size  of  the  cylinders  ? 

Answer.  The  cylinders  must  be  large  enough  so  that  with  the  maxi- 
mum steam  pressure  in  the  boiler,  they  can  always  turn  the  driving- 
wTheels  when  the  locomotive  is  starting,  but  their  size  should  not  be  much 
greater  than  is  needed  to  turn  the  wheels,  because  if  they  are  the  pressure 
on  the  pistons  is  liable  to  cause  the  wheels  to  slip  on  the  rails. 

Question  708.  How  much  force  must  be  exerted  to  turn  the  driving- 
wheels  ? 

Answer.  The  maximum  force  which  must  be  exerted  to  turn  the 
wheels  is  that  required  to  overcome  their  friction  or  adhesion  to  the  rails, 
and  make  them  slip.  The  adhesion,  as  explained  in  Chapter  X,  varies 
from  one-third  to  one-sixth  of  the  weight  bearing  on  the  rails.  The  cyl- 
inders should,  therefore,  be  so  proportioned  that  the  greatest  tractive 
force  which  will  be  exerted  by  the  pistons  will  be  equal  to  the  maximum 
adhesion.  As  it  is  only  under  very  favorable  conditions  that  the  adhe- 
sion of  the  driving-wheels  is  equal  to  a third  of  the  weight  on  them,  in 
calculating  the  size  of  the  cylinders  the  adhesion  may  be  assumed  to  be 
one-fourth  the  weight  on  the  wheels. 

With  an  ordinary  slide  valve  and  link  motion  working  in  full  gear,  the 
greatest  average  pressure  in  the  cylinders  at  a slow  speed  is  about  90  per 
cent,  of  the  boiler  pressure.  From  this  the  greatest  mean  tractive  force 
may  be  calculated  by  the  rule  given  in  answer  to  Question  447.*  As  the 

* A committee  of  the  Master  Mechanics’  Association  appointed  to  report  on  this  subject  have 
recommended  that  the  pressure  in  the  cylinders  be  taken  at  85  per  cent,  of  the  boiler  pressure ; 
but  in  order  to  have  the  cylinders  as  nearly  of  the  right  size  as  possible  during  all  conditions  of 
the  tires,  they  based  their  calculations  on  the  diameter  of  the  tires  when  half  worn  out.  As  this 
introduces  an  element  of  confusion  in  comparing  the  dimensions  of  different  engines,  it  has 
been  preferred  to  base  the  calculations  on  a somewhat  higher  percentage  of  boiler  pressure  and 
on  the  original  diameter  of  the  tires,  which  gives  nearly  the  same  results  and  avoids  the  con- 
fusion referred  to, 


542 


Catechism  of  the  Locomotive. 


stroke  of  the  pistons  is  usually  known,  the  problem  generally  is  to  deter- 
mine the  diameter  of  the  cylinders,  which  with  an  average  pressure  of  90 
per  cent,  of  the  maximum  boiler  pressure,  will  give  a tractive  force  equal 
to  the  adhesion  of  the  wheels,  assuming  that  to  be  equal  to  one-fourth 
the  weight  on  them.  Having  the  adhesion  and  knowing  the  boiler  press- 
ure, the  tractive  force  for  different  sized  cylinders  can  be  calculated  until 
the  diameter  is  found  which  will  be  of  the  right  size.  But  as  this  would 
be  tedious,  the  following  rule  which  gives  the  right  diameter  with  one 
calculation,  will  be  found  convenient : 

To  GET  THE  AREA  OF  THE  PISTONS  OF  A LOCOMOTIVE. 

Multiply  one-fourth  of  the  whole  weight  (in  pounds)  which 

RESTS  ON  THE  RAILS  UNDER  THE  DRIVING-WHEELS  BY  THE  CIRCUM- 
FERENCE (IN  INCHES)  OF  THOSE  WHEELS.  THEN  MULTIPLY  90  PER  CENT. 
OF  THE  MAXIMUM  BOILER  PRESSURE  (IN  POUNDS  PER  SQUARE  INCH)  BY 
FOUR  TIMES  THE  STROKE  OF  THE  PISTONS  (IN  INCHES),  AND  DIVIDE  THE 
FIRST  PRODUCT  BY  THE  SECOND.  THE  QUOTIENT  WILL  BE  THE  AREA  OF 
EACH  PISTON  IN  SQUARE  INCHES.* 

To  apply  this  rule  to  an  actual  example,  an  engine  with  pistons  18  inches 
in  diameter  and  24  inches  stroke,  and  with  driving-wheels  feet=66 
inches  in  diameter,  loaded  with  64,000  lbs.  = 32  tons  and  a maximum 
boiler  pressure  of  150  lbs.  per  square  inch,  will  be  taken.  The  circum- 

* This  rule  has  been  worked  out  algebraically  as  follows  : 

Let  A = Area  of  one  piston  (in  square  inches). 

P = Maximum  boiler  pressure  (per  square  inch). 

p = Mean  pressure  (per  square  inch)  in  the  cylinder. 

S = Stroke  of  piston  (in  inches). 

C = Circumference  of  driving-wheels  (in  inches). 

W = Total  weight  on  rails  below  all  the  driving-wheels  (in  pounds). 

As p is  assumed  to  be  = .90  P the  tractive  force,  by  the  rule  given  in  answer  to  Question  406, 
A x .90  P x 4 S 
will  be  . 

C 

The  adhesion  has  been  assumed  to  be  equal  to  14  JU,  and  as  the  tractive  force  and  the  adhe- 
sion should  be  equal,  we  have 

A*  .90  PX  4 S 

= 14 

C 

from  which  we  have 

14  WX  c 

A = . 

.90  P X 4 S 

It  is  not  easy  to  give  a demonstration  of  this  rule  without  the  use  of  algebra,  and  those  not 
acquainted  with  that  branch  of  mathematics  must  accept  the  rule  on  faith. 


Proportions  of  Locomotives. 


543 


ference  of  these  wheels  will  be  207.3  inches,  so  that  by  the  rule  we  will 
have : 

64,000 

=16,000  x 207.3=3,316,800, 

4 

and  150  x .90  x4  x 24=12,960, 

3,316,800 

and  =255.9=area  of  cylinder. 

12,960 

Having  the  area  the  diameter  can  readily  be  ascertained  by  calculation, 
or  from  a table  of  diameters  and  areas.  In  this  case  the  diameter  is  18 
inches  very  nearly. 

Question  709.  What  are  the  three  elements  which  determine  the  size 
of  the  cylinders  ? 

Answer.  From  what  has  been  said  it  will  be  seen  that  the  size  of  the 
cylinders  is  governed  by,  first,  the  weight  on  the  driving-wheels ; second, 
the  diameter  of  those  wheels  ; and,  third,  the  steam  pressure. 

QUESTION  710.  Are  the  sizes  of  cylinders  generally  determined  by  these 
considerations  ? 

Answer.  No ; many  locomotive  superintendents  regard  the  expansive 
action  of  the  steam  in  the  cylinders  as  of  more  importance  in  determining 
their  size  than  any  other  consideration,  and  therefore  they  make  the 
cylinders  larger  than  the  above  rule  would  indicate  they  should  be.  In 
other  cases  cylinders  are  made  of  considerably  smaller  sizes  than  would 
be  given  by  the  rule.  Caprice,  prejudice  and  accident,  seem  to  have  had 
considerable  influence  in  determining  the  proportions  of  cylinders. 

QUESTION  711.  In  what  way  can  we  compare  the  relative  sizes  of  cyl- 
inders, taking  into  account  the  weight  on  the  driving-wheels,  their  size,  and 
the  steam  pressure  ? 1 

Answer.  The  method  of  doing  this  can  be  best  explained  by  taking, 
as  an  example,  a standard  passenger  locomotive  with  cylinders  18  inches 
diameter  and  24  inches  stroke,  driving-wheels  5|-  feet=66  inches  diameter, 
and  with  64,000  lbs.  of  load  on  these  wheels.  The  circumference  of  such 
wheels  is  207.3  inches,  and  if  they  do  not  slip  the  locomotive  will  move 
that  distance  on  the  rails  while  the  wheels  revolve  once.  At  the  same  time 
each  piston  will  sweep  through  its  cylinder  twice,  and  therefore  during 
one  revolution  of  the  wheels  four  times  one  cylinder  full  of  steam  is  used. 
The  cubical  space  that  a piston  18  inches  diameter  and  24  inches  stroke 
sweeps  through  in  moving  from  one  end  of  the  cylinder  to  the  other  is 


544 


Catechism  of  the  Locomotive. 


equal  to  6,107  cubic  inches,  so  that  in  one  revolution  of  the  wheels 
6,107x4=24,428  cubic  inches  of  steam  are  used.  If,  then,  we  divide 
24,428  by  207.3  inches,  the  distance  that  the  locomotive  moves  during  one 
revolution  of  its  driving-wheels,  it  will  give  us  the  amount  of  steam  used 
to  move  the  locomotive  and  train  one  inch.  That  is,  24,428-^207.3=117.8. 

* It  will  thus  be  seen  that  a locomotive  of  the  dimensions  given,  and  with 
64,000  lbs.  or  32  tons  (of  2,000  lbs.)  of  adhesive  weight,  has  117.8  cubic 
inches  of  cylinder  capacity*  to'  move  it  one  inch.  If  the  locomotive  had 
only  half  as  much  weight  on  the  driving-wheels,  it  would  have  only  half 
as  much  adhesion  and  could  pull  only  half  as  much  load,  and  would  there- 
fore require  only  half  as  much  steam,  and  consequently  need  only  half  the 
cylinder  capacity  of  the  other  locomotive.  If  there  was  three-quarters  or 
a third  as  much  adhesive  weight,  the  cylinder  capacity  should  also  be 
three-quarters  or  a third.  In  other  words,  the  cylinder  capacity  should 
be  proportioned  to  the  adhesive  weight.  If,  then,  we  divide  the  number 
of  cubic  inches  of  steam  consumed  while  the  engine  moves  one  inch  by 
the  number  of  tons  (of  2,000  lbs.)  of  adhesive  weight,  it  will  give  us  the 
number  of  cubic  inches  of  cylinder  capacity  per  ton  of  adhesive  weight. 
Applying  this  to  the  preceding  example,  117.8-^32  = 3.68  cubic  inches  will 
be  the  cylinder  capacity  per  ton  of  adhesive  weight  and  per  inch  of  the 
circumference  of  its  driving-wheels.  This  quantity  has  been  named  the 
modulus  of  propulsion,  which  can  be  calculated  by  the  following  rule  : 

Multiply  the  area  of  one  piston  (in  square  inches)  by  the 

STROKE  (IN  INCHES)  AND  THE  PRODUCT  BY  FOUR.  DIVIDE  THIS  PRO- 
DUCT BY  THE  CIRCUMFERENCE  OF  THE  DRIVING-WHEELS  (IN  INCHES) 
AND  BY  THE  WELGHT  (IN  TONS  OF  2,000  LBS.)  ON  ALL  THE  DRIVING- 
WHEELS.  The  quotient  will  be  the  modulus  of  propulsion. 

This  modulus  varies  considerably  in  different  locomotives.  Thus  in 
some  consolidation  engines  built  for  the  Denver  & Rio  Grande  Railroad, 
the  cylinders  were  20  inches  diameter  and  24  inches  stroke,  the  wheels  46 
inches  diameter  with  103,000  lbs.  of  weight  on  them.  The  modulus  of 
propulsion  on  these  engines  is  4.05,  whereas  some  ten-wheeled  passenger 
engines  on  the  Michigan  Central  Railroad,  have  cylinders  19x24  inches, 
wheels  68  inches  diameter,  with  96,000  lbs.  on  the  driving-wheels,  and, 
consequently,  have  a modulus  of  propulsion  of  only  2.65. 

To  get  a measure  of  the  cylinder  capacity  which  will  also  take  the 

* The  cylinder  capacity  is  the  space  swept  through  by  the  two  pistons.  In  the  above  illustra- 
tions what  is  meant  is,  that  the  average  space  in  the  cylinder  swept  through  by  the  piston  is 
J17.8  cubic  inches  for  each  inch  that  the  locomotive  advances, 


Proportions  of  Locomotives. 


545 


steam  pressure  into  account,  we  should  multiply  the  modulus  of  propul- 
sion by  the  maximum  boiler  pressure  per  square  inch.  This  product  has 
been  named  the  modulus  of  traction.  Thus  in  the  first  example  the  boiler 
pressure  was  assumed  to  be  150  lbs.,  and  therefore  3.68  x 150=552,  in  the 
second  it  was  140  lbs.,  so  that  4.05  x 140=567.  Experience  seems  to  indi- 
cate that  a modulus  of  traction  of  about  550  will  give  very  good  results  in 
practice. 

It  should  be  remarked  here  that  it  is  unimportant,  so  far  as  the  power 
of  the  locomotive  is  concerned,  whether  the  cylinders  have  a large  diam- 
eter and  a short  stroke  or  a small  diameter  and  a long  stroke,  provided 
the  cubical  contents  are  the  same.  Thus,  cylinders  17^  inches  in  diameter 
and  with  20  inches  stroke  would  have  almost  exactly  the  same  capacity, 
and  the  same  power  would  be  exerted  with  them  as  with  cylinders  16  x 24 
inches  ; the  only  difference  would  be  that  with  the  cylinder  of  the  largest 
diameter  the  pressure  on  the  piston,  and  consequently  on  the  crank-pin 
journal,  and  the  strain  on  the  parts  would  be  greater  than  with  the  smaller 
cylinder.  The  difference  in  pressure  would,  however,  be  exactly  compen- 
sated by  the  loss  or  gain  in  the  leverage  exerted  through  the  driving- 
wheels  on  the  rails. 

Question  712.  What  circumstances  should  determine  the  size  of  loco- 
motive boilers  ? 

Answer.  They  should  be  proportioned  to  the  amount  of  adhesive 
weight,  and  to  the  speed  at  which  the  locomotive  is  intended  to  work. 
Thus,  a locomotive  with  a great  deal  of  weight  on  the  driving-wheels 
could  pull  a heavier  load,  and  would,  by  the  above  rule  for  proportioning 
the  cylinders,  have  a greater  cylinder  capacity  than  one  with  little  adhe- 
sive weight,  and  would  therefore  consume  more  steam,  and  therefore 
should  have  a larger  boiler.  It  is  also  obvious  that  if  a locomotive  like 
that  shown  in  Plate  III  should  have  a boiler  just  large  enough  to  furnish 
steam  when  running  at  the  rate  of  20  miles  an  hour,  it  would  be  too  small 
if  the  locomotive  ran  40  miles  an  hour,  the  train  resistance  being  the  same 
in  both  cases.  Driving-wheels  5 feet  in  diameter  would  at  20  miles  per 
hour  make  112  revolutions  per  minute,  and  would  therefore  consume  448 
cylinders  full  of  steam.  At  40  miles  per  hour  double  the  number  of  revo- 
lutions would  be  made,  and  consequently  twice  the  quantity  of  steam 
would  be  used,  and  therefore  the  boiler  should  have  twice  the  steam- 
producing  capacity.  If,  therefore,  we  know  the  size  of  a boiler  required 
for  a given  amount  of  adhesive  weight  and  a given  speed,  we  can  easily 
calculate  the  boiler  capacity  for  any  other  weight  and  speed. 


546 


Catechism  of  the  Locomotive. 


Question  713.  What  circumstances  usually  determine  the  size  and 
proportion  of  locomotive  boilers  ? 

Answer.  The  weight  and  dimensions  of  locomotive  boilers  are  in  nearly 
all  cases  determined  by  the  limits  of  weight  and  space  to  which  they  are 
necessarily  confined.  It  may  be  stated  generally  that  within  these  limits 
a locomotive  boiler  cannot  be  made  too  large.  In  other  words,  boilers 
should  always  be  made  as  large  as  is  possible  under  the  conditions  that 
determine  the  weight  and  dimensions  of  the  locomotives. 

Question  714.  On  what  does  the  steam-generating  capacity  of  a boiler 
depend  ? 

Answer.  First,  upon  the  size  of  its  grate  and  fire-box,  because  more 
fuel  can  be  burned  in  a large  fireplace  than  in  a small  one ; second,  on  the 
amount  of  heating  surface  to  which  the  products  of  combustion  are 
exposed  ; and,  third,  on  the  draft  produced  by  the  blast  or  exhaust  steam. 
Of  course  the  amount  of  steam  generated  is  also  dependent  upon  a great 
variety  of  other  circumstances,  such  as  the  nature  of  the  combustion,  the 
firing,  the  arrangement  of  the  fire-box,  grates,  exhaust-pipes,  smoke-box, 
etc.,  and  the  condition  of  the  heating  surfaces  ; but  these  have  nothing  to 
do  with  the  size  of  the  boiler. 

Question  715.  What  are  the  proportions  of  boilers  used  in  locomotives 
like  that  which  is  represented  in  Plates  III-  V ? 

Answer.  The  area  of  the  grate  is  usually  about  18  square  feet,  and  the 
total  heating  surface  about  1,600  square  feet. 

Question  716.  At  what  speed  are  such  engines  usually  run  ? 

Answer.  The  speed  varies  so  much  under  different  circumstances,  that 
it  is  impossible  to  give  even  approximately  the  average  speed  of  such 
engines. 

Question  717.  In  what  respects  is  the  operation  of  locomotive  boilers 
different  from  that  of  nearly  all  other  steam  boilers  ? 

Answer.  The  amount  of  steam  generated  in  proportion  to  the  amount 
of  heating  surface  is  much  greater  in  locomotive  boilers  than  in  any  other 
kind.  To  produce  combustion  which  will  be  sufficiently  active  to  gener- 
ate the  requisite  quantity  of  steam,  the  fire  must  be  stimulated  by  the 
blast  created  by  the  exhaust  steam  to  a degree  unknown  in  other  kinds  of 
boilers.  So  rapid  is  the  movement  of  the  products  of  combustion  that  a 
smaller  proportion  of  the  heat  is  imparted  to  the  water  contained  in  the 
boiler,  and  consequently  a less  amount  of  water  is  evaporated  in  propor- 
tion to  any  given  amount  of  fuel  than  in  boilers  in  which  combustion  is 
less  violent.  The  combustion  is  often  less  complete,  because  the  strong 


Proportions  of  Locomotives. 


547 


draft  does  not  allow  time  for  a perfect  combination  of  the  gases  which 
produce  combustion. 

The  supply  of  steam  which  a locomotive  boiler  must  furnish  is  also 
much  more  irregular  than  the  demands  made  upon  any  other  kind  of 
boiler.  At  one  time  the  fire  must  be  urged  to  the  greatest  possible 
intensity,  in  order  to  furnish  steam  enough  to  pull  a train  up  a steep  grade. 
When  the  top  is  reached  the  demand  ceases,  and  the  boiler  can  be  cooled. 
The  load  which  a locomotive  can  pull  over  a given  line  of  road  is  usually 
limited  by  the  utmost  capacity  of  the  boiler  to  supply  steam  at  these 
critical  periods. 

Question  718.  What  relation  is  there  betwee?i  this  irregular  action 
and  the  size  of  the  boiler  ? 

Answer.  The  smaller  the  boiler,  or  rather  the  larger  the  amount  of 
steam  which  must  be  generated  in  a given  time  in  proportion  to  the  heat- 
ing surface,  the  more  must  the  fire  be  urged ; and,  therefore,  the  smaller 
the  boiler  in  proportion  to  the  work  it  must  do,  the  less  will  be  its 
economy.  In  order  to  produce  a rapid  combustion  in  a small  boiler,  it  is 
necessary  to  contract  the  exhaust  nozzles  in  order  to  create  a draft  strong 
enough.  In  doing  this  the  back  pressure  on  the  pistons  is  very  much 
increased,  and  when  the  blast  becomes  very  violent  a great  deal  of  solid 
coal  is  carried  through  the  tubes  and  escapes  at  the  smoke-stack  uncon- 
sumed. At  the  same  time  large  quantities  of  unconsumed  gases  escape, 
because  there  is  not  time  for  combustion  to  take  place  in  the  fire-box. 
The  fact  that  with  a violent  draft  the  flame  and  smoke  are  in  contact  with 
the  heating  surface  for  a sensibly  shorter  period  of  time  also  has  its  influ- 
ence, as  less  heat  will  Le  imparted  to  the  water  if  the  products  of  combus- 
tion are  only  of  a second  instead  of  in  passing  through  the  tubes. 

There  is  another  consideration  which  should  be  taken  into  account  in 
this  connection,  which  is,  that  if  a boiler  is  so  small  that  it  is  worked 
nearly  up  to  its  maximum  capacity  at  all  times,  it  will  be  impossible  to 
accumulate  any  reserve  power  in  it  in  the  form  of  water  heated  to  a high 
temperature  to  be  used  as  occasion  may  require.  With  a boiler  having  a 
great  amount  of  heating  surface  and  capacity  for  carrying  a large  quantity 
of  water,  the  latter  can  be  heated  at  times  when  the  engine  is  not  work- 
ing hard,  and  the  heat  thus  stored  up  in  the  water  can  then  be  used  when 
it  is  most  needed.  Thus  we  will  suppose  that  to  pull  a train  of  cars  on 
a level  250  lbs.  of  steam  are  consumed  per  mile.  On  a grade  of  30  feet 
per  mile  the  resistance  will  be  three  times  what  it  is  on  a level,  and  there- 
fore three  times  the  quantity  of  steam  will  be  consumed,  so  that  the  boiler 


548 


Catechism  of  the  Locomotive. 


must  then  evaporate  750  lbs.  of  water  per  mile.  Now,  to  convert  250  lbs. 
of  water  heated  up  to  a temperature  due  to  130  lbs.  of  effective  pressure,, 
or  355.6  degrees,  into  steam  of  that  pressure  will  require  216,575  units  of 
heat.  If  at  the  same  time  that  this  steam  is  being  consumed,  we  pump 
into  the  boiler  250  lbs.  of  water  of  a temperature  of  60  degrees,  73,900 
more  units  of  heat  will  be  needed  to  raise  the  water  to  the  temperature 
due  to  130  lbs.  effective  pressure,  so  that  on  the  level  part  of  the  road  it 
would  be  necessary  to  transmit  to  the  water  in  the  boiler  216,575  + 73,900 
=290,475  units  of  heat  in  a mile.  If  there  is  no  room  in  the  boiler  for 
storing  a surplus  quantity  of  hot  water,  it  will  be  necessary  on  a grade  as 
fast  as  the  steam  is  consumed  to  feed  an  equivalent  amount  of  cold  water 
to  take  the  place  of  that  which  was  converted  into  steam,  so  that  on  a 30 
feet  grade  it  would  be  necessary  to  convert  at  the  rate  of  750  lbs.  of  hot 
water  into  steam  in  a mile,  which  would  require  649,725  units  of  heat,  and 
at  the  same  time  an  equal  amount  of  cold  water  must  be  heated  to  a tem- 
perature due  to  the  pressure  of  the  steam,  which  would  require  221,700 
more  units.  So  that  it  will  be  necessary  to  transmit  at  the  rate  of  871,425 
units  of  heat  to  the  water  per  mile.  Now,  if  the  boiler  was  so  large  that 
more  water  could  be  pumped  into  it  and  heated  than  was  used  on  the 
level  portion  of  the  road,  and  cOuld  be  stored  up  in  the  boiler  for  future 
use,  the  pumps  might  be  either  partly  or  entirely  shut  off  when  the  engine 
was  working  the  hardest  on  the  grade.  In  this  way,  instead  of  being 
obliged  to  convert  hot  water  into  steam,  and  at  the  same  time  heat  an 
equivalent  amount  of  cold  feed-water,  there  would  be  a surplus  of  hot 
water  stored  up  already  heated.  It  would  therefore  only  be  necessary  to 
convert  this  hot  water  into  steam,  which  will  require  a transmission  of 
heat  to  the  water  at  the  rate  of  649,725  units  of  heat  instead  of  871,425. 
It  must  be  remembered  that  on  nearly  all  roads  there  are  certain  difficult 
places  which  practically  limit  the  capacity  of  the  locomotives  on  that  line. 
If,  therefore,  the  capacity  of  the  engines  can  be  increased  at  those  points, 
their  capacity  over  the  whole  line  is  increased.  It  will  be  seen  by  the 
above  illustration  that  by  having  a large  boiler  it  is  necessary  for  it  to  do> 
very  much  less  work  at  the  critical  period,  when,  as  every  locomotive, 
engineer  knows,  it  is  often  of  the  utmost  importance  to  make  use  of  every 
possible  available  means  in  order  to  pull  the  train.  It  is  true  that  on  a- 
very  long  grade  the  supply  of  surplus  hot  water  would  soon  be  exhausted, 
but  even  in  such  cases  there  is  usually  one  place,  owing  to  a curve  or 
other  cause,  which  is  more  difficult  to  surmount  than  any  other,  and 
then  it  will  be  necessary  to  use  more  steam  for  a short  time  than  the  loco- 


Proportions  of  Locomotives. 


549 


•motive  can  generate  if  the  boiler  is  fed  continuously.  For  such  occasions  a 
surplus  of  water  can  be  used.  But  even  if  the  resistance  is  equal  over  the 
whole  length  of  the  incline,  still  the  large  boiler  will  have  the  advantage, 
because  it  can  at  all  times  generate  more  steam  than  a smaller  one.  It 
may,  therefore,  we  think,  safely  be  assumed  that  locomotive  boilers  should 
always  be  made  as  large  as  the  weight  of  the  locomotive  will  permit. 

Question  719.  What  effect  does  the  size  of  the  driving-wheels  have 
upon  the  combustion  and  evaporation  of  locomotive  boilers  ? 

Answer.  As  small  wheels  make  more  revolutions  in  running  a given 
•distance  than  large  ones,  there  will  be  more  strokes  of  the  piston  with  the 
former  than  with  the  latter,  if  the  locomotive  in  both  cases  runs  at  the 
same  speed.  As  smaller  cylinders  can  be  used  with  small  wheels,  the 
blast  up  the  chimney  is  then  composed  of  a larger  number  of  discharges 
of  steam,  but  each  one  is  of  a less  quantity  of  steam  than  when  larger  wheels 
and  cylinders  are  employed.  In  the  one  case  the  “puffs”  of  steam  are  many 
and  small,  and  in  the  latter  few  and  large.  If  the  cylinders  are  proportioned 
by  the  rule  which  has  been  given  for  that  purpose,  the  amount  of  steam 
discharged  in  running  any  given  distance  will  be  the  same  with  engines  of 
the  same  weight  having  large  and  those  with  small  wheels,  the  only  dif- 
ference being  that  it  will  be  subdivided  into  a greater  number  of  dis- 
charges in  the  one  case  than  in  the  other.  Now,  it  is  found  that  the 
draft  of  engines  is  much  more  effective  on  the  fire  when  the  blast  is  thus 
subdivided,  that  is  when  small  wheels  and  cylinders  are  used,  than  it  is 
with  large  ones,  and  therefore  more  steam  is  generated  with  the  former 
than  with  the  latter. 

Question  720.  What  relation  is  there  between  the  size  of  the  wheels 
and  that  of  the  boiler  ? 

Answer.  As  has  been  explained,  the  size  of  the  boiler  is  limited  by  the 
weight  of  the  locomotive.  The  boiler  and  its  attachments  of  an  Ameri- 
can type  of  locomotive,  when  the  former  is  filled  with  water,  weigh  about 
half  as  much  as  the  locomotive  ; therefore,  unless  we  increase  the  weight 
of  the  latter  or  decrease  the  weight  of  the  machinery,  we  cannot  increase 
the  size  of  the  boiler.  Now,  large  wheels  are  heavier  than  small  ones ; 
they  require  larger  cylinders,  stronger  connections,  heavier  frames,  and  in 
fact  nearly  all  the  parts  of  the  machinery  used  with  large  wheels  must  be 
heavier  than  are  required  when  small  wheels  are  used.  Therefore,  by  de- 
creasing the  size  of  the  wheels  all  the  other  parts  of  the  engine  proper  can 
be  made  lighter  than  is  possible  if  large  wheels  are  used,  and  thus  the  size 
and  weight  of  the  boiler  can  be  increased  without  increasing  the  whole 


550 


Catechism  of  the  Locomotive. 


weight  of  the  locomotive.  There  is,  of  course,  a practical  limit  below 
which  the  size  of  the  wheels  cannot  be  reduced,  because  the  speed  of  the 
piston  would  become  so  great  as  to  be  injurious  to  the  machinery.  By 
reducing  the  stroke,  however,  with  the  diameter  of  the  wheels,  the  evil 
referred  to  may  be  obviated  to  a great  extent.  Cylinders  with  a large 
diameter  and  comparatively  small  stroke  have  also  the  advantage  that 
there  is  less  surface  exposed  to  radiation  of  heat  than  there  is  in  cylinders 
in  which  these  proportions  are  reversed. 


CHAPTER  XXX. 

COMBUSTION. 

Question  721.  What  is  meant  by  combustion  ? 

Answer.  By  combustion  is  meant  the  phenomenon  ordinarily  called 
burning,  as  when  a piece  of  wood  or  coal  or  a candle  is  burned.  In  reality 
combustion  is  a union  of  one  of  the  “ chemical  elements  A oxygen,  of  which 
the  atmosphere  is  composed,  with  the  elements  which  constitute  the  fuel. 

Question  722.  What  is  meant  by  the  term  “ chemical  eleme7it  ? ” 

Answer.  The  science  of  chemistry  has  demonstrated  that  nearly  all 
substances  by  which  we  are  surrounded  are  composed  of  certain  other 
substances,  which  latter,  as  far  as  is  now  known,  are  not  compounds,  and 
are  therefore  called  elementary  substances , or  chemical  elements.  Thus,  the 
air  by  which  we  are  surrounded  is  composed  of  two  gases,  called  nitrogen 
and  oxygen  ; water  is  composed  of  hydrogen  and  oxygen,  and  coal  chiefly 
of  carbon  and  hydrogen.  There  are  now  over  sixty  of  these  elementary 
substances  known.  From  no  one  of  them  have  chemists  been  able  to 
extract  any  material  excepting  the  substance  itself.  These  elementary 
substances  will  combine  with  others  so  as  to  form  what  is  apparently  a 
new  material,  but  on  weighing  it,  it  will  be  found  that  the  weight  of  the 
new  material  is  greater  than  the  original  elementary  substance,  showing 
that  something  was  added  to  it  which  effected  the  change.* 

Question  723.  To  what  fact  is  this  combination  or  combustion  of  ele- 
mentary substances  due  ? 

Answer.  It  is  owing  to  the  fact — the  exact  reason  for  which  is,  perhaps, 
not  yet  understood  fully — that  the  atoms  of  the  elementary  substances  of 
which  fuel  is  composed,  that  is,  hydrogen  and  carbon,  and  the  atoms  of 
oxygen,  which  forms  part  of  the  atmosphere  by  which  we  are  surrounded, 
attract  each  other  with  great  energy  when  they  are  excited  into  activity 
by  the  application  of  heat. 

Question  724.  What  phenomenon  always  attends  chemical  combination 
of  substances  ? 

Answer.  Such  combination  always  gives  out  heat,  whereas  their  separa- 
tion absorbs  heat.  It  has  further  been  proved  by  actual  experiment  that 


* “The  New  Chemistry,”  by  J.  P.  Cooke,  Jr. 


552 


Catechism  of  the  Locomotive. 


the  amount  of  heat  liberated  by  the  chemical  union  of  the  same  quantity 
or  number  of  atoms  of  two  or  more  substances  is  always  the  same,  and 
that  when,  by  any  cause,  the  atoms  thus  joined  are  separated,  exactly  the 
same  amount  of  heat  is  absorbed.* 

Question  725.  In  what  proportions  do  the  ele7nentary  substances  com- 
bine with  each  other  ? 

Answer.  It  is  a law  of  chemistry  that  each  of  the  elementary  substances 
combines  with  the  others  in  certain  definite  proportions  only.  These 
proportions  vary  for  the  different  elements,  and  have  been  determined 
with  great  accuracy  by  chemists.  Thus,  8 parts  by  weight  of  oxygen 
will  combine  with  nitrogen  and  form  atmospheric  air,  or  the  same  pro- 
portion of  oxygen  will  combine  with  hydrogen  and  form  water,  or  with 
carbon  and  form  carbonic  acid,  which  is  the  deadly  gas  which  accumulates 
at  the  bottom  of  wells. 

Oxygen  always  combines  with  other  substances  in  the  proportion  of  8 parts 
by  weight,  or  by  some  simple  multiple  of  8,  that  is,  8 x 2= 16  parts,  or  8 x 3=24 
parts,  etc.  Each  of  the  other  elementary  substances  also  has  a certain 
fixed  proportion  in  which  it  combines  with  others,  and  this  proportion, 
which  is  usually  given  by  weight,  is  represented  by  a number  called  its 
chemical  equivalent.  Thus  8 is  the  chemical  equivalent  of  oxygen.  Car- 
bon combines  with  other  elements  in  proportions  of  6,  and  nitrogen  in 
proportions  of  14,  so  that  6 and  14  are  the  chemical  equivalents  of  carbon 
and  nitrogen.  Now  8 parts  by  weight  of  oxygen  can  be  made  to  combine 
with  14  parts  of  nitrogen,  or  8 x 2 = 16  parts  of  oxygen  will  combine  with 
14  of  nitrogen,  but  it  is  impossible  to  make,  say  12  parts  of  oxygen  com- 
bine with  14  parts  of  nitrogen.  We  can  combine  14  x 2=28  parts  of  nitro- 
gen with  8 parts  of  oxygen,  but  no  chemical  process  can  make,  say  10  or 
20  parts  of  nitrogen  combine  with  8 parts  of  oxygen.  If  20  parts  of  nitro- 
gen are  mixed  with  8 parts  of  oxygen,  then  the  latter  will  combine  with 
14  parts  of  the  former,  but  6 parts  of  nitrogen  will  be  left,  and  chemical 
combination  will  then  cease. 

The  following  table  will  give  the  chemical  equivalents  of  the  principal 
elements  which  enter  into  the  process  of  combustion  of  the  fuel  used  in 

locomotives  I Chemical  equiva- 

lent by  weight. 

Oxygen 8 

Nitrogen 14 

Hydrogen 1 

Carbon * 6 

Sulphur 16 

* “ The  New  Chemistry,”  by  J.  P.  Cooke,  Jr. 


Combustion. 


553 


QUESTION  726.  What  effect  do  the  proportions  in  which  elements  are 
s combined  have  upon  the  substances  which  are  produced  by  the  combination  ? 

Answer.  A change  in  the  proportions  in  which  the  elements  are  com- 
bined usually  alters  the  entire  nature  of  the  substance,  so  far  at  least  as  it 
affects  our  senses.  For  instance,  oxygen  unites  chemically  with  nitrogen 
in  different  proportions,  forming  five  distinct  substances,  each  essentially 
different  from  the  others,  thus  : 

14  parts  of  Nitrogen  with  8 of  Oxygen  forms  Nitrous  Oxide. 


14 

“ “ 16 

“ Nitric  Oxide. 

14 

“ “ 24 

“ Hyponitrous  Acid. 

14 

“ 32 

“ Nitrous  Acid. 

14 

“ “ 40 

“ Nitric  Acid. 

We  here  find  the  elements  of  the  air  we  breathe,  by  a mere  change  in 
the  proportions  in  which  they  are  united,  forming  distinct  substances, 
which  differ  from  each  other  as  much  as  laughing  gas  (nitrous  oxide) 
does  from  that  most  destructive  agent,  ?iitric  acid , commonly  called  aqua- 
fortis* 

Question  727.  What  occurs  when  a fresh  supply  of  bituminous  coal  is 
ihrown  on  a bright  fire  in  a fire-box  of  a locomotive  ? 

Answer.  The  fresh  coal  is  first  heated  by  the  fire,  and  if  a sufficient 
quantity  is  thrown  in  to  prevent  the  immediate  formation  of  flamed  a 
volume  of  gas  or  vapor,  usually  of  a dark  yellow  or  brown  color,  is  given 
off.  The  quantity  evolved  will  be  greatest  when  the  coal  is  very  small. 
This  gas  or  vapor  is  commonly  called  smoke,  but  it  does  not  deposit  soot, 
and  in  reality  is  not  true  smoke.  If  a sheet  of  white  paper  be  held  over 
the  vapor  as  it  escapes  from  the  coal  and  there  is  no  flame,  the  sheet  will 
become  slowly  coated  with  a sticky  matter  of  brown  color  difficult  to 
remove,  and  having  a strong  tarry  or  sulphurous  smell ; whereas,  if  a sheet 
.of  paper  is  held  over  smoke  it  will  quickly  be  covered  with  black  soot. 
The  color  and  smell  left  on  the  paper  in  the  first  case  are  due  to  the  tarry 
-matter,  sulphur,  and  other  ingredients  in  the  gas.  Deprived  of  the  color- 
ing matters,  the  vapor  is  a chemical  mixture  of  2 parts  of  hydrogen  and  6 
parts  of  carbon,  and  is  called  carburetted  hydrogen,  and  is  nearly  the  same 
as  the  colorless  gas  by  which  our  houses  are  lighted.:}:  A similar  gas  is 
generated  at  the  wick  of  a burning  candle  or  lamp,  and  is  consumed  in 

* “ Combustion  of  Coal  and  the  Prevention  of  Smoke,”  by  C.  Wye  Williams. 

t Usually  if  more  than  two  or  three  shovels  full  are  thrown  in,  there  will  be  no  immediate 
formation  of  flame. 

.%  “A  Treatise  on  Steam  Boilers,”  by  Robert  Wilson. 


554 


Catechism  of  the  Locomotive. 


the  flame.  Before  the  gas  is  expelled  from  the  fresh  coal,  the  latter  must 
be  heated  to  a temperature  of  about  1,200°,  so  that  if  100  lbs.  at  a tempera- 
ture of  50°  is  put  on  the  fire,  23,000  units  of  heat  will  be  absorbed  to  heat 
the  coal.*  Nor  is  this  all,  as  has  been  explained  in  answer  to  Question 
106,  when  any  substance  is  vaporized  a certain  amount  of  heat  apparently 
disappears,  which  has  been  called  the  heat  of  evaporation  or  of  gasifica- 
tion. Average  bituminous  coal  contains  about  80  per  cent,  of  carbon,  5 
per  cent,  of  hydrogen,  and  15  per  cent,  of  other  substances  usually  re- 
garded as  impurities.  When  the  coal  is  heated  up  to  about  1,200°,  the  5 
per  cent,  of  hydrogen  unites  with  three  times  its  weight  of  carbon,  and 
thus  20  per  cent,  of  the  coal  is  converted  into  the  gas  described.  In  this 
process  a large  amount  of  heat  is  absorbed  or  becomes  latent,  as  it  does 
when  water  or  any  other  substance  is  converted  into  vapor.  It  will  there- 
fore be  seen  that  the  first  effect  of  putting  fresh  coal  on  the  fire  is  to  cool 
the  fire.  This  fact  has  an  important  bearing  on  the  question  of  combus- 
tion and  will  be  referred  to  hereafter. 

Question  728.  How  can  the  process  of  the  combustion  of  the  gas 
generated  from  the  coal  be  best  explained  ? 

Answer.  As  this  gas  is  substantially  the  same  as  ordinary  illuminating 
gas,  the  manner  in  which  it  burns  can,  perhaps,  be  made  clearer  by  ex- 
amining the  combustion  of  an  ordinary  gas-light.  As  stated  before, 
combustion  is  a chemical  union  of  the  oxygen  which  forms  one  of  the 
elements  of  the  air  with  the  hydrogen  and  carbon  of  the  fuel,  which,  in 
this  case,  form  gas.  It  should  be  clearly  kept  in  mind  that  combustion  is 
the  result  of  this  union,  and  that  the  oxygen  is  as  essential  to  combustion 
as  coal  or  gas,  and,  in  fact,  is  the  fuel  of  combustion,  just  as  much  as  coal 
or  gas  is.  If  we  were  to  conduct  a pipe  from  the  external  air  into  a vessel 
filled  with  coal  gas  we  could  light  the  air  and  it  would  burn  in  the  gas  as 
the  gas  burns  in  the  air. 

It  will  be  noticed,  however,  that  before  either  the  gas  or  the  air  will 
burn,  they  must  be  lighted.  Air  and  gas,  even  if  mixed  together  in  the 
same  vessel,  will  not  burn  unless  they  are  lighted.  This  can  be  done  by 
the  flame  of  any  burning  material,  or  with  a piece  of  metal  heated  to  a 
very  high  temperature,  or  by  an  electric  spark.  In  other  words  it  may  be 
said  that  the  atoms  of  the  two  gases  must  be  excited  into  activity  by  the 
application  of  heat,  that  is,  what  is  called  an  igniting  temperature  must 
be  communicated  to  them  before  chemical  combination  will  begin.  The 

* The  quantity  of  heat  required  to  heat  coal  is  only  about  one-fifth  that  needed  to  heat  the 
same  weight  of  water  to  the  same  temperature. 


Combustion. 


555 


chief  feature  which  distinguishes  combustion  from  other  chemical  union 
is  the  circumstance  that  the  heat  generated  during  the  combination  is 
sufficient  to  maintain  an  igniting  temperature,  and  the  necessity  of  doing 
so  in  order  to  continue  the  process  is  of  very  great  importance  in  the 
combustion  of  coal  in  locomotive  boilers,  as  will  be  shown  hereafter. 

Question  729.  How  does  an  ordinary  gas-light  bum  after  it  is  lighted? 

Answer.  Under  ordinary  conditions  the  hydrogen,  which  is  the  most 
combustible  of  the  two  elements  of  which  coal  gas  is  formed,  is  the  first 
to  burn.  This  part  of  the  combustion  forms  the  lower  bluish  part  of  the 
flame.  The  combustion  of  the  hydrogen  thus  separates  it  from  the 
carbon,  which  is  then  set  free;  and  as  carbon  is  never  found  in  a gaseous 
condition  when  uncombined  with  other  substances,  it  at  once  assumes  the 
form  of  fine  soot  when  the  hydrogen  is  burned  away  from  it.  This  fine 
soot,  or  pulverized  carbon,  is,  however,  intensely  heated  by  the  combus- 
tion of  the  hydrogen.  Now  carbon,  when  heated  to  an  igniting  tempera- 
ture will,  if  brought  into  contact  with  a sufficient  quantity  of  oxygen, 
combine  with  it  or  be  burned.  Each  particle  of  carbon  thus  becomes  a 
glowing  centre  of  radiation,  throwing  out  its  luminous  rays  in  every 
direction.  The  sparks  last,  however,  but  an  instant,  for  the  next  moment 
they  are  consumed  by  the  oxygen,  which  is  aroused  to  full  activity  by  the 
heat,  and  only  a transparent  gas  rises  from  the  flame.  But  the  same 
process  continues ; other  particles  succeed,  which  become  heated  and 
ignited  in  their  turn,  and  it  is  to  this  combustion  of  the  solid  particles  of 
carbon  that  the  light  which  is  given  out  by  a gas-burner  or  candle  is  due.* 

Question  730.  Why  does  a gas-burner,  candle  or  other  flame  sometimes 
smoke  ? 

Answer.  Because  the  supply  of  oxygen  is  then  insufficient  to  consume 
the  particles  of  solid  carbon  which  are  set  free  and  which  then  assume 
the  form  of  soot.  This  can  be  illustrated  if  we  cut  a hole  in  a card,  d d, 
fig.  466,  so  as  to  fit  over  an  ordinary  gas-burner,  b.  If  we  then  light  the 
gas  and  place  a glass  chimney,  a a,  over  the  burner  and  let  it  rest  on  the 
card,  it  will  be  found  that  the  flame  will  at  once  begin  to  smoke,  because 
very  little  air  can  then  come  in  contact  with  the  flame,  and  therefore  when 
the  fine  particles  of  carbon  are  set  free  by  the  combustion  of  the  hydrogen, 
instead  of  being  burned,  as  they  would  be  if  the  air  with  its  supply  of 
oxygen  were  not  excluded  from  the  flame  by  the  chimney,  they  escape 
unconsumed  in  the  form  of  fine  black  powder  or  soot.  If  we  raise  the 
chimney  up  from  the  card,  as  shown  in  fig.  467,  so  as  to  leave  enough 


* “ The  New  Chemistry,”  by  J.  P.  Cooke,  Jr. 


556 


Catechism  of  the  Locomotive. 


space  between  them  at  the  bottom  of  the  chimney  to  permit  air  to  enter, 
as  indicated  by  the  darts,  c c,and  supply  the  flame  with  oxygen,  the  smoke 
will  instantly  cease,  as  the  particles  of  carbon  are  then  consumed.  The 
same  principle  is  illustrated  in  an  ordinary  kerosene  lamp.  It  is  well 
known  that  without  a chimney  the  flames  of  nearly  all  such  lamps  smoke 
Intolerably,  whereas  with  a glass  chimney  and  the  peculiarly  formed 
deflector  which  surrounds  the  wick,  the  light  burns  without  smoke  unless 
the  wick  is  turned  up  high.  The  effect  of  the  chimney  is  to  produce  a 
draft  which  is  thrown  against  the  flame  by  the  deflector,  and  thus  a suffi- 
cient supply  of  oxygen  is  furnished  to  consume  all  the  particles  of  carbon, 
whereas,  without  the  draft  produced  by  the  chimney,  the  supply  of  oxygen 
is  insufficient  to  ignite  all  the  carbon,  which  then  escapes  in  the  form  of 
smoke  or  soot. 


Fig.  466.  Fig.  467. 

Gas-Light. 


It  must  not,  however,  be  hastily  assumed  that  if  the  flame  does  not  give 
out  a bright  light,  therefore  the  combustion  is  not  complete.  As  has 
already  been  stated,  the  light  of  the  gas  flame  is  due  to  the  presence  of 
burning  particles  of  solid  carbon,  which  is  set  free  by  the  combustion  of 
the  hydrogen  with  which  it  is  combined.  After  it  is  separated  from  the 


Combustion. 


557 


hydrogen  it  immediately  assumes  a solid  form.  If  the  coal  gas  is  mixed 
with  a sufficient  quantity  of  air  before  it  is  burned,  the  oxygen  in  the 
latter  will  be  in  such  intimate  contact  with  the  former  that  the  difference 
of  affinity  of  oxygen  for  the  carbon  and  hydrogen  does  not  come  into 
play,  and  as  there  is  enough  oxygen  for  all,  the  carbon  is  burned  before 
it  is  set  free,  and  as  there  are  then  no  solid  particles  in  the  flame,  there  is 
no  light.  This  is  illustrated  by  what  is  called  a “ Bunsen  burner,”  fig.  468„ 


Fig.  468.  Bunsen  Burner.  Fig.  469.  Candle. 


which  is  much  used  in  chemical  laboratories.  It  consists  of  a small  tube 
or  burner,  a , which  is  placed  inside  of  another  larger  tube,  b.  The  latter 
has  holes,  c c,  a little  below  the  top  of  the  small  tube.  The  current  of 
gas  escaping  from  the  small  tube  draws  the  air  in  through  the  holes,  c cr 
and  produces  what  is  called  an  induced  current  of  air  in  the  large  tube. 
This  air  enters  through  the  holes,  c c,  and  is  mixed  with  the  gas  in  the 
tube,  b,  and  the  mixture  is  burned  at  d.  The  flame  from  such  a burner 
gives  hardly  any  light,  but  the  heat  is  intense,  as  is  shown  if  a metal  wire 
is  held  in  it  for  a few  seconds,  which  will  very  soon  glow  with  heat. 

QUESTION  731.  What  important  difference  is  there  m the  structure  of 
the  flame  of  a Bunsen  burner  and  that  of  an  ordinary  gas-burner  or 
candle? 

Answer.  The  gas  which  escapes  from  the  mouth,  d,  of  the  pipe,  b, 
fig. 468,  is  mixed  with  air,  and  therefore  contains  within  itself  the  elements 


558 


Catechism  of  the  Locomotive. 


which  only  need  to  combine  to  produce  combustion;  whereas,  with  an 
ordinary  gas-burner  or  candle,  the  air  comes  in  contact  with  the  flame 
only  from  the  outside,  or  on  its  surface.  This  is  shown  better,  perhaps, 
in  the  flame  of  an  ordinary  candle.  The  heat  of  such  a flame  distills  a 
gas  from  the  melted  tallow,  which  is  similar  in  nature  to  that  which 
escapes  from  coal  at  a high  temperature.  Now,  by  observing  the  candle 
very  closely,  it  will  be  seen  that  at  the  bottom,  close  to  the  wick,  there  is 
very  little  combustion,  as  the  gas  there  first  escapes  from  the  wick  and  is 
not  heated  to  a sufficiently  high  temperature  to  burn  freely.  A little 
above  the  lowermost  part  the  flame  is  of  a pale  blueish  color,  which  is 
due  to  the  combustion  of  the  hydrogen.  Above  that,  where  the  carbon 
is  set  free,  its  particles  glow  with  heat  imparted  by  the  burning  hydrogen, 
and  are  then  consumed  by  uniting  with  the  oxygen  of  the  air.  The  com- 
bustion occurs  only  at  the  surface  of  the  flame,  the  inside  being  a mass 
of  combustible  gas  which  cannot  burn  until  it  in  turn  comes  in  contact 
with  the  oxygen  of  the  air.  This  can  be  proved  by  inserting  one  end  of 
a small  tube,  a , fig.  469  (a  pipe  stem  will  do),  which  is  open  at  both  ends, 
into  the  flame.  The  combustible  gas  will  then  escape  at  the  other  end,  b, 
and  can  easily  be  lighted  with  a match. 

It  will  be  found  that  the  flame  from  the  Bunsen  burner  is  much  more 
intense  than  that  of  an  ordinary  candle  or  gas-burner.  The  reason  of  this 
is  that  combustion,  as  already  stated,  takes  place  through  the  whole  mass 
of  its  flame,  whereas  an  ordinary  flame  burns  only  at  its  surface.  Common 
gas-jets  are  therefore  arranged  so  that  the  flames  will  be  flat,  thus  expos- 
ing as  much  surface  to  the  air  as  possible,  and,  as  explained  in  answer  to 
Question  545,  in  describing  the  lamps  for  head-lights,  their  burners  are 
usually  made  with  a circular  wick,  through  the  centre  of  which  a current 
of  air  circulates.  This  arrangement  exposes  a larger  surface  of  the  flame 
to  the  air,  and  also  with  the  aid  of  a chimney  furnishes  an  abundant 
supply  for  combustion.  In  stationary  boilers,  with  long  flues  of  a large 
sectional  area,  the  flame  will  often  extend  for  thirty  feet,  showing  that 
while  combustion  is  going  on  only  at  the  surface  of  the  flame,  it  takes  a 
long  time  to  complete  the  process.  The  same  thing  is  shown  if  a gas- 
burner  is  made  with  a single  round  hole.  The  flame  will  then  be  very 
long  and  liable  to  smoke  at  the  top. 

Question  732.  From  the  preceding  considerations  what  may  we  infer 
to  be  necessary  in  order  to  consume  coal  gas  perfectly  ? 

Answer.  In  the  first  place  there  must  exist  a certain  degree  of  what 
chemists  call  “ molecular  activity,”  which  is  produced  by  heat,  or  what  we 


Combustion. 


559 


have  called  the  igniting  temperature.  The  necessity  of  this  is  sufficiently 
obvious  with  ordinary  gas-burners,  as  they  must  always  be  lighted  before 
they  will  burn.  Now  imagine  that  it  was  required  to  burn  gas  which  was 
issuing  from  a hundred  jets,  of  every  variety  of  size,  in  a violent  wind 
storm,  or  gusts  of  wind.  Obviously  it  would  be  necessary  to  keep  a 
lighted  torch  all  the  time  to  relight  those  which  would  be  blown  out. 
The  gas  in  a locomotive  fire-box  is  in  reality  burned  in  a storm  of  wind 
more  violent  than  any  natural  one.  It  is  therefore  necessary  to  be  con- 
stantly ready  to  relight  the  streams  of  gas  which  the  faintest  breath  would 
extinguish,  or  those  of  larger  volume  which  have  absorbed  a great  deal  of 
heat  and  thus  reduced  the  temperature  at  the  time  and  place  of  their 
birth,  when  they  assumed  the  gaseous  form,  as  was  explained  in  answer  to 
Question  727.  To  relight  them  with  certainty  it  is  necessary  to  keep  a 
constant  temperature  in  the  fire-box  high  enough  to  ignite  the  gas  which 
escapes  or  is  distilled  from  the  coal. 

Second.  That  the  chemical  change  in  combustion  consists  simply  in 
the  union  of  the  elements  burned  with  the  oxygen  of  the  air;  and,  there- 
fore, to  burn  the  gas  perfectly,  without  smoke  or  waste,  enough  air  must 
be  furnished  to  supply  all  the  oxygen  which  will  combine  with  the  fuel. 

Third.  That  the  air  must  be  mixed  with  the  gas,  otherwise  combustion 
will  occur  only  at  the  surface  of  the  flame,  and  will  therefore  be  so  slow 
that  much  of  the  gas  will  escape  unconsumed. 

It  must  be  clearly  kept  in  mind  that  no  one  or  two  of  these  require- 
ments alone,  without  the  third,  will  burn  coal  perfectly.  What  is  needed 
is  all  three  in  combination.  A very  common  error  is  to  suppose  that 
passing  smoke  over  a hot  fire,  or,  in  other  words,  maintaining  an  igniting 
temperature,  will  alone  effect  perfect  combustion ; or  that  if  a sufficient 
supply  of  air  is  admitted,  without  an  igniting  temperature  in  the  fire-box, 
the  fuel  will  be  burned  completely.  Neither  of  them  will  accomplish  the 
object  alone,  and  the  gas  and  air  must  at  the  same  time  be  thoroughly 
mixed  with  the  burning  gas  in  the  fire-box. 

Question  738.  What  substances  are  produced  by  the  combustion  of 
coal  gas? 

Answer.  The  hydrogen  of  coal  gas  unites  during  combustion  with 
oxygen  in  the  proportion,  as  indicated  by  their  chemical  equivalents,  of  1 
part  by  weight  of  hydrogen  with  8 parts  of  oxygen,  the  product  of  which 
is  water.  Of  course  at  the  high  temperature  at  which  the  gases  combine 
or  burn,  the  water  is  produced  in  the  form  of  steam.  That  water  or  steam 
is  one  of  the  products  of  combustion  is  shown  every  cold  evening,  when 


560 


Catechism  of  the  Locomotive. 


the  insides  of  shop  show-windows  are  covered  with  moisture,  which  is*, 
due  to  the  steam  that  is  given  off  by  the  burning  gas-lights  or  lamps, 
inside,  and  is  then  condensed  against  the  cold  glass. 

Carbon  combines  with  oxygen  in  two  proportions : first,  6 parts  of  the 
former  will  unite  with  8 of  the  latter,  forming  what  is  called  carbonic 
oxide  ; or,  6 parts  of  carbon  will  combine  with  16  parts  of  oxygen,  forming 
carbonic  acid  gas  or  carbonic  dioxide  or  carbonic  anhydride,  as  it  is  called 
in  some  of  the  new  books  on  chemistry.  It  is  probable  that  the  former 
compound,  that  is,  carbonic  oxide,  is  never  or  very  rarely  formed,  in  the 
flame  of  coal  gas ; but,  as  will  be  seen  hereafter,  is  a very  common  and. 
wasteful  product  of  the  combustion  of  the  solid  portion  of  the  coal  which 
is  left  after  the  gas  is  expelled  from  it.  When  there  is  not  enough  oxygen, 
for  the  perfect  combustion  of  the  carbon  in  the  flame,  it  smokes,  and  the. 
carbon  escapes  in  the  form  of  soot.  This,  as  will  be  shown,  may  in  a. 
locomotive  fire-box  help  to  form  carbonic  oxide  after  it  leaves  the  flame. 

Question  734.  What  remains  in  the  coal  after  all  the  gas  is  expelled 
by  heat  ? 

Answer.  What  remains  is  ordinarily  called  coke,  which,  with  the 
exception  of  some  incombustible  substances,  such  as  sand,  ashes,  and 
cinders,  which  the  coal  contains,  is  nearly  pure  carbon. 

Question  735.  What  is  the  chemical  process  of  the  combustion  of  coke?. 

Answer.  The  solid  carbon  of  the  coke  when  raised  to  an  igniting  tem- 
perature, or,  in  other  words,  on  being  lighted,  unites  with  the  oxygen  in 
one  of  the  two  proportions  already  given  ; that  is,  if  the  supply  of  oxygen 
is  sufficient,  6 parts  of  the  carbon  of  the  coke  unite  with  16  parts  of  oxygen, 
forming  carbonic  acid  gas,  or  carbonic  dioxide.  If,  however,  the  layer  of 
fuel  on  the  grates  is  thick,  or  the  supply  of  air  is  comparatively  small,  there- 
will  not  be  enough  oxygen  to  supply  16  parts  of  the  latter  to  each  6 parts 
of  the  carbon,  so  that  when  that  occurs,  instead  of  combining  in.  that  pro- 
portion, and  thus  forming  carbonic  dioxide,  8 parts  of  oxygen  will  unite  with 
6 parts  of  carbon  and  form  carbonic  oxide.  Now  it  should  be  carefully 
kept  in  mind  that  the  heat  of  combustion  is  due  to  the  union,  or,  as  it  is 
sometimes  expressed,  it  is  the  clashing  together  of  the  molecules  of  the 
two  elements  which  unite.  If,  therefore,  only  half  the  quantity  of  oxygen, 
unites  with  6 parts  of  carbon,  evidently  there  will  be  less  heat  evolved 
than  there  would  be  if  twice  that  amount  of  oxygen  combined  with  the 
carbon.  From  carefully  made  experiments,  it  was  found  that  the  total 
heat  of  the  combustion  of  1 lb.  of  carbon,  when  converted  into  carbonic 
oxide , was  4,400  units,  whereas  when  it  was  converted  into  carbonic  dioxide 


Combustion. 


561 


14,500  units  were  given  out.  It  will  thus  be  seen  that  it  is  extremely 
wasteful  to  burn  coal  without  a sufficient  supply  of  air  to  produce  carbonic 
dioxide.  The  danger  of  waste  from  this  cause  is  also  increased  by  the 
fact  that  carbonic  oxide  is  colorless  and  odorless,  and  therefore  its  pro- 
duction is  not  apparent,  especially  as  most  persons  have  the  impression 
that  when  there  is  no  smoke  from  a fire  combustion  is  then  complete. 
It  burns  with  a blue  or  yellowish  flame  when  air  is  admitted  into  the  fire- 
box, and  its  presence  can  often  be  detected  by  these  phenomena  when  the 
furnace  door  is  opened. 

QUESTION  736.  How  can  the  requisite  quantity  of  air  be  supplied  to  the 
fire  in  a locomotive  fire-box  ? 

Answer.  It  is  done  in  two  ways  : one  way  is  to  keep  but  little  coal  on 
the  grates,  or,  in  the  phraseology  of  firemen,  to  “ carry  a light  fire.”  The 
other  method  is  to  admit  fresh  air  above  the  fire.  If  the  latter  plan  is 
adopted  when  the  supply  of  air  through  the  grates  is  insufficient  for  per- 
fect combustion,  the  carbonic  oxide  will  unite  with  the  oxygen  of  the  air 
above  the  fire,  and  thus  a second  combustion  will  take  place,  the  product 
of  which  will  be  carbonic  dioxide.  It  must  be  kept  in  mind,  however, 
that  not  only  must  there  be  enough  air  supplied  to  the  fire  to  consume 
the  coke,  but  the  gases  which  are  distilled  from  the  coal  must  also  be 
supplied  with  oxygen  in  order  to  effect  their  perfect  combustion.  Even 
if  enough  air  is  admitted  to  consume  the  coke  perfectly,  if  the  carbonic 
dioxide  thus  formed  is  mixed  with  large  quantities  of  smoke  above  the 
fire,  the  solid  carbon  or  soot  of  the  smoke  may  then  combine  with  the 
dioxide  and  thus  form  carbonic  oxide,  if  there  is  not  enough  fresh  air 
present  to  furnish  the  requisite  oxygen  for  the  carbon  in  the  smoke.  A 
very  common  error  is  to  suppose  that  smoke  can  be  burned  by  passing  it 
over  or  through  a very  hot  fire.  The  smoke  may  thus  be  made  invisible, 
it  is  true,  but  it  does  not  therefore  follow  that  it  is  perfectly  consumed. 

Question  737.  Is  it  possible  to  admit  too  much  air  into  the  fire-box  of 
a locomotive  ? 

Answer.  Yes ; probably  all  the  air  that  is  admitted  which  is  not  neces- 
sary for  combustion,  or,  in  other  words,  the  oxygen  of  which  does  not 
combine  with  the  fuel,  instead  of  increasing,  diminishes  the  amount  of 
steam  which  is  generated.  It  does  this  in  two  ways : first,  by  reducing 
the  temperature  of  the  gases  in  contact  with  the  heating  surfaces,  and 
second,  by  increasing  the  volume  or  quantity  of  the  gases  which  must 
pass  through  the  tubes.  Heat  is  transmitted  through  the  heating  surface 
of  a boiler  in  proportion  to  the  difference  of  the  temperature  of  the  pro- 


562 


Catechism  of  the  Locomotive. 


ducts  of  combustion  on  one  side,  and  the  water  on  the  other.*  Thus,  if 
the  temperature  of  the  water  on  one  side  is  250  degrees,  and  the  hot  gases 
on  the  other  is  500,  there  will  be  only  half  as  much  heat  transmitted  to 
the  water  in  a given  time  as  there  would  be  if  the  gases  had  a tempera- 
ture of  750  degrees.  If  the  volume  of  gases  is  doubled  by  the  admission 
of  too  much  air,  then  obviously  in  order  to  pass  through  the  tubes  they 
must  move  at  double  the  velocity,  so  that  not  only  is  their  temperature 
reduced,  but  the  time  they  are  in  contact  with  the  heating  surface  is 
diminished  in  like  proportion.  This  is  shown  by  the  effect  of  opening 
the  furnace  door,  or  of  allowing  the  fire  to  burn  away  so  that  portions  of 
the  grate  are  left  uncovered.  The  volume  of  cold  air  which  will  in  either 
of  these  cases  enter  the  fire-box  will  be  so  great  that  the  pressure  of  the 
steam  in  the  boiler  will  begin  to  fall  at  once. 

Question  738.  What  determines  the  amount  of  air  which  must  be  ad- 
mitted to  the  fire-box  of  a locomotive  to  effect  perfect  combustion  ? 

Answer.  This  depends  chiefly  upon  the  rate  of  combustion — that  is,  the 
number  of  pounds  of  coal  consumed  per  hour  on  each  square  foot  of  grate 
surface.  Of  course  if  100  lbs.  is  burned  it  will  require  twice  the  supply  of 
air  that  would  be  needed  if  only  50  lbs  were  burned. 

Question  739.  How  should  the  air  be  admitted  so  as  to  burn  the  coai 
perfectly? 

Answer.  In  burning  bituminous  coal  it  has  been  shown  that  there  are 
two  distinct  bodies  to  be  dealt  with,  the  one  coke,  a solid , the  other  coal 
gas,  which  is,  of  course,  a gaseous  body.  The  combustion  of  each  of  these 
is  necessarily  a distinct  process.  If  the  requisite  quantity  of  air  is  sup- 
plied to  the  burning  coke,  or  solid  portions  of  the  coal,  it  will,  as  has  been 
shown,  be  converted  into  carbonic  dioxide,  and  thus  be  perfectly  con- 
sumed. If  the  supply  of  air  is  insufficient,  the  product  of  the  combustion 
will  be  carbonic  oxide,  which  is  very  wasteful.  If,  for  example,  there  is  a 
thick  layer  of  coke  on  the  grate,  the  air  will  enter  and  unite  with  the 
lower  layer  of  coal  and  form  carbonic  dioxide,  but  as  it  rises  there  will 
not  be  enough  air  to  supply  oxygen  to  the  carbon,  and  another  equivalent 
of  the  latter  will  therefore  combine  with  the  carbonic  dioxide  and  form 
carbonic  oxide.  It  is  evident,  though,  that  the  thinner  the  fire,  the  easier 
it  is  for  air  to  pass  through  it,  and  consequently  the  greater  will  be  the 
quantity  which  will  enter  the  fire-box.  Nothing  would  seem  easier,  then, 
than  to  regulate  the  thickness  of  the  fire  on  the  grates,  so  that  just  the 
needed  amount  of  air  would  pass  through  it.  If  coke  alone  was  to  be 

* This  law  is  perhaps  not  absolutely  correct,  but  is  near  enough  for  our  present  illustration. 


Combustion. 


563 


burned,  undoubtedly  very  perfect  combustion  would  be  (and  has  been) 
effected  in  this  way ; but  if  a charge  of  fresh  coal,  say  100  lbs.,  is  thrown 
on  the  fire,  coal  gas  is  very  soon  generated  and  escapes  into  the  fire-box. 
This  gas  needs  an  additional  amount  of  air  for  its  combustion.  It  would 
seem  that  this  could  be  supplied  by  reducing  the  thickness  of  the  fire  still 
further,  so  that  more  air  would  pass  through  it  than  was  needed  for  the 
combustion  of  the  coke  alone.  If  this  was  done,  then  too  much  air  would 
pass  through  the  coke  after  the  gases  had  all  escaped  from  the  fresh 
coal  and  were  burned.  Besides,  the  passage  of  the  air  would  be  the  most 
restricted  after  the  fresh  charge  had  been  put  on  the  fire,  just  at  the  time 
when  the  most  is  needed.  This  difficulty  might  be  overcome  if  a constant 
supply  of  fresh  coal  just  equal  to  that  consumed  were  kept  on  the  fire  all 
the  time,  and  the  thickness  of  fuel  on  the  grates  was  then  regulated  so  as 
to  admit  just  air  enough  for  the  combustion  of  the  coke  and  also  that  of 
the  gases,  the  production  of  which  would  then  be  uniform.  An  approxi- 
mation to  this  method  of  feeding  the  fire  is,  in  fact,  what  is  aimed  at  on 
most  locomotives,  and  probably  the  best  practical  results  are  produced  by 
that  method. 

Two  difficulties  are,  however,  encountered  in  this  method.  In  the  first 
place,  it  is  impossible  to  feed  a fire  continuously  with  a shovel.  There 
will  be  intervals  between  the  charges  which  are  thrown  in,  so  that  the 
supply  is  not  uniform,  even  if  the  charges  do  not  consist  of  more  than  a 
portion  of  a shovelful  at  a time;  and,  if  the  fire  was  fed  in  this  way  as 
uniformly  as  possible,  it  would  then  be  necessary  to  open  the  furnace  door 
every  time  fresh  coal  was  put  on  the  fire,  and  so  much  cold  air  would 
thus  be  admitted  that  more  would  be  lost  by  lowering  the  temperature  of 
the  boiler  than  wrould  be  gained  by  the  improved  combustion. 

Another  difficulty,  also,  is  encountered  in  this  method  of  burning  coal 
in  locomotives.  In  order  to  admit  enough  air  through  the  fire  it  is  neces- 
sary to  keep  the  latter  so  thin  on  the  grates  that  the  violent  draft  pro- 
duced by  the  blast  lifts  the  coal  from  the  grate-bars  and  carries  the  lighter 
particles  through  the  flues  unconsumed.  It  is  thus  extremely  difficult  to 
keep  the  grate  uniformly  covered  with  coal,  and  if  it  is  not,  the  air  will 
enter  in  irregular  and  rapid  streams  or  masses  through  the  uncovered 
parts,  and  at  the  very  time  when  it  should  be  there  most  restricted.  Such 
a state  of  things  at  once  bids  defiance  to  all  regulation  or  control,  so  that 
it  is  found  almost  uniformly  that  firemen  of  locomotives  keep  enough  coal 
on  the  grates  to  avoid  the  danger  of  “losing  their  fire,”  as  they  express 
it — that  is,  having  all  the  burning  coal  drawn  through  the  tubes  by  the 


564 


Catechism  of  the  Locomotive. 


blast.  Now  on  the  control  of  the  supply  of  air  depends  all  that  human 
skill  can  do  in  effecting  perfect  coiiibustion  and  economy  ; and  unless  the 
supply  of  fuel  and  the  quantity  on  the  bars  can  be  regulated,  it  will  be  im- 
possible to  control  the  admission  of  the  air.* 

Another  method  of  feeding  locomotive  boilers  is  to  pile  up  the  coal  in 
the  back  part  in  a thick  layer  as  shown  in  fig.  476,  and  slope  it  downward 
toward  the  front,  so  that  there  is  a comparatively  thin  fire  in  front.  The 
mass  piled  up  at  the  door  becomes  converted  into  coke,  and  the  produc- 
tion of  gas  from  the  coal  is  more  gradual  and  uniform  than  it  is  when 
only  a small  quantity  is  thrown  in  at  a time,  and  therefore  a more  uniform 
supply  of  air  is  needed  for  its  combustion.  But  it  is  apparent  that  very 
little  air  can  pass  through  the  thick  heap  of  coal  at  the  back  part  of  the 
fire-box,  and  that  therefore  all,  or  nearly  all  the  air  which  enters  it  must 
come  in  through  a comparatively  small  portion  of  the  grate.  It  will  of 
course  be  difficult  to  admit  the  requisite  quantity,  for  the  reasons  already 
stated. 

It  is,  therefore,  plain  that  it  is  practically  impossible  to  admit  enough 
air  through  the  grates  to  effect  a constantly  perfect  combustion  of  bitu- 
minous coal.  It  is,  then,  necessary  to  admit  a portion  of  the  air  above 
the  fire.  When  this  is  done  the  air  thus  admitted  must  be  thoroughly 
mixed  with  the  gases,  to  effect  perfect-  combustion  and  in  order  to  be 
able  to  enter  into  chemical  combination,  or,  in  other  words,  to  burn,  the 
gases  must  combine  with  the  air  at  an  igniting  temperature.  If  too  much 
air  is  admitted,  it  will  reduce  the  temperature  in  the  fire-box  so  much 
that  the  gases  will  not  ignite ; or,  if  it  is  admitted  in  strong  currents,  the 
air  and  the  gases  will  flow  side  by  side  like  the  currents  of  two  streams  of 
water,  the  one  muddy  and  the  other  clear,  which,  as  is  well  known,  mingle 
very  slowly.  Besides,  if  a hot  stream  of  gas  encounters  a strong  stream 
of  cold  air  and  comes  in  contact  with  it  only  at  its  surface,  the  latter  will 
be  cooled  down  below  the  igniting  temperature;  whereas,  if  the  two  had 
been  intimately  mixed  in  the  right  proportion,  the  whole  mixture  would 
have  been  hot  enough  to  burn.  It  is  therefore  important  that  the  air 
which  is  admitted  above  the  fire  should  enter  the  fire-box  in  many  small 
jets.  None  of  the  openings  for  its  admission  should  exceed  half  an  inch 
in  diameter.  With  the  violent  draft  in  a locomotive  fire-box  there  is  an 
extremely  brief  period  of  time  for  chemical  combination  to  take  place 
after  the  gases  are  expelled  from  the  coal  and  before  they  are  hurried  into 
the  tubes.  As  the  chemical  action  between  the  gases  and  the  oxygen  can 


* “ The  Combustion  of  Coal,”  by  Wye  Williams. 


Combustion. 


565 


only  take  place  when  the  two  are  in  intimate  contact,  too  much  pains 
cannot  be  taken  to  distribute  the  currents  of  admitted  air  and  thus  mix 
them  with  the  combustible  gases.  In  many  cases  means  are  adopted  to 
delay  the  air  and  the  gases  in  the  fire-box  so  as  to  give  them  time  for 
chemical  combination  or  combustion  before  entering  the  tubes. 

Question  740.  Does  any  combustio?i  take  place  after  the  gases  enter  the 
tubes  ? 

Answer . Very  little ; as  the  flames  are  extinguished  soon  after  they 
enter. 

QUESTION  741.  Why  are  the  flames  extinguished  in  the  tubes  ? 

Answer.  They  are  then  in  contact  with  large  quantities  of  incombusti- 
ble gas  and  beyond  the  reach  of  a supply  of  air  ; besides,  the  temperature 
of  the  tubes  which  are  surrounded  with  water  is  so  low  that  the  flame  is 
soon  cooled  down  below  an  igniting  temperature. 

Question  742.  What  temperature  is  necessary  to  ignite  coal  gas  or 
produce  flame  ? 

Answer.  A temperature  about  equal  to  that  of  red-hot  iron  is  needed, 
as  can  easily  be  shown  by  the  fact  that  a gas-light  can  be  ignited  with  a 
bright  red-hot  poker,  but  will  not  light  after  the  poker  is  cooled  down  to 
a dark  color. 

Question  743.  Are  there  any  parts  of  the  fire-box  where  the  tempera- 
ture is  probably  below  the  igniting  point  ? 

Answer.  Yes;  along  the  sides  and  ends  near  the  plates,  which  are 
covered  with  water  on  the  opposite  side.  At  these  points  the  coal  is 
usually  “ dead,”  as  it  remains  at  too  low  a temperature  to  burn.  For  this 
reason,  in  some  cases  a space  of  from  8 to  12  inches  on  each  side  and 
still  more  at  the  ends  of  the  grates  is  made  of  solid  plates,  without  any 
openings,  and  therefore  called  “ dead-grates,"  so  that  no  cold  air  can  enter 
at  those  points.  These  plates  are  made  sloping  downward  from  the  sides 
toward  the  centre  of  the  fire-box,  so  that  the  coal  which  falls  on  them  and 
is  thus  coked  can  easily  be  raked  toward  the  middle  of  the  fire.  This 
arrangement  of  dead  plates  often  improves  the  combustion,  and  results  in 
greater  economy  of  fuel.  When  dead  plates  are  useo  the  reduction  of  the 
area  of  the  openings  between  the  grate-bars  for  the  admission  of  air  can 
usually  be  compensated  by  making  the  bars  narrower  or  the  spaces 
between  them  wider. 

QUESTION  744.  What  should  be  the  condition  of  the  coal  when  it  is  put 
on  the  fire  ? 

Answer.  It  is  true  of  the  coal  as  well  as  of  the  gases  that  the  chemical 


566 


Catechism  of  the  Locomotive. 


action  between  it  and  the  oxygen  can  only  take  place  when  the  two  are  in 
intimate  contact,  and  therefore  the  rapidity  and  completeness  of  combus- 
tion and  intensity  of  heat  will  be  increased  by  increasing  the  number  of 
points  of  contact,  or  by  reducing  the  size  of  the  fuel.  . The  coal  should 
therefore  be  broken  up,  but  not  so  small  as  to  fall  between  the  grate-bars 
or  be  carried  out  of  the  fire-box  by  the  blast. 

Question  745.  What  a7nount  of  air  must  be  admitted  to  the  fire  to 
effect  perfect  co7nbustion  f 

ATtswer.  It  was  stated  that  average  bituminous  coal  contains  about  80 
per  cent,  carbon,  5 per  cent,  of  hydrogen,  and  15  per  cent,  of  other  sub- 
stances. As  a large  proportion  of  the  latter  are  incombustible,  we  will 
confine  ourselves  for  the  present  to  the  consideration  of  the  combustion 
of  the  hydrogen  and  carbon  alone. 

The  hydrogen,  as  has  been  explained,  unites  with  oxygen  in  the  propor- 
tion by  weight  of  1 part  of  the  former  to  8 parts  of  the  latter,  and  the 
product  of. this  union  is  water  or  steam.  As  36  parts  of  air  contain  only  8 
of  oxygen,  in  order  to  burn  the  hydrogen  it  must  be  supplied 
with  36  times  its  weight  of  air. 

In  order  to  burn  the  carbon  perfectly  it  must,  as  has  been  explained,  be 
converted  into  carbonic  dioxide,  which  consists  of  6 parts  of  carbon  and 
16  of  oxygen  ; and  as  air  consists  of  28  parts  of  nitrogen  to  every  8 of 
oxygen,  we  must  furnish  72  parts  of  air  to  every  6 of  carbon,  or,  in  other 
words,  CARBON  needs  12  times  its  weight  of  air  for  its  perfect 
combustion. 

Every  pound  of  average  bituminous  coal,  therefore,  requires  1.8  lbs.  of 
air  to  burn  its  hydrogen,  and  9.6  lbs.  for  the  carbon,  or  11.4  for  both.  As 
a portion  of  the  other  substances  of  which  coal  is  composed,  besides  the 
oxygen  and  hydrogen,  which  others  have  been  classed  as  impurities,  are 
combustible,  there  will  be  no  material  error  if  we  estimate  the  amount  of 
air  required  for  the  combustion  of  bituminous  coal  at  12  lbs.  per  lb.  of 
fuel.  As  each  cubic  foot  of  air  weighs  0.08072  lb.,  12  lbs.  will  be  equal  to 
12 

= 148.6  cubic  feet  of  air, 

0.08072 

or,  for  the  sake  of  even  figures  and  a quantity  which  can  easily  be  remem- 
bered, we  will  say  150  cubic  feet  of  air  are  needed  for  the  com- 
bustion OF  EACH  POUND  OF  COAL.  This  is  the  theoretical  quantity  of 
air  which  is  needed  for  combustion.  Now,  unfortunately,  the  process  of 
combustion  in  the  fire-boxes  of  locomotives  is  one  in  which  any  very 


Combustion. 


567 


exact  combination  of  the  substances  which  unite  is  not  possible  with  the 
appliances  which  are  now  employed.  If,  therefore,  we  admitted  the  exact 
amount  of  air  given  above,  while  some  portions  of  the  fire  where  com- 
bustion was  not  very  active  might  have  more  air  than  is  needed,  other 
portions  would  have  too  little  ; and  if  the  air  is  not  very  thoroughly  mixed, 
the  flame  and  burning  coal  may  be  surrounded  with  the  products  of  com- 
bustion, which  would  exclude  the  air  and  thus  reduce  its  effect  upon  the 
fire.  For  this  reason,  besides  the  air  required  to  furnish  the  oxygen, 
necessary  for  the  complete  combustion  of  the  fuel,  it  is  also  necessary  to 
furnish  an  additional  quantity  of  air  for  the  dilution  of  the  gaseous  pro- 
ducts of  combustion,  which  would  otherwise  prevent  the  free  access  of  air 
to  the  fuel.  The  more  minute  the  division  and  the  greater  the  velocity 
with  which  the  air  rushes  among  the  fuel,  the  smaller  is  the  additional 
quantity- of  air  required  for  dilution.  In  locomotive  boilers,  although  this 
quantity  has  not  been  exactly  ascertained,  there  is  reason  to  believe  that 
it  may  on  an  average  be  estimated  at  about  one-half  of  the  air  required 
for  combustion.*  We  would,  therefore,  have  as  the  quantity  of  air  needed 
for  combustion 

150 

150  H = 225  cubic  feet. 

2 

This  estimate,  it  will  be  seen,  is  roughly  made,  and  doubtless  with  very 
careful  firing  and  perfect  appliances  a smaller  quantity  of  air  would  give 
better  results.  It  is  probable  that  the  supply  of  air  required  for  dilution 
varies  considerably  in  different  arrangements  of  the  fire-box  and  for  differ- 
ent kinds  of  fuel,  and  it  is  possible  that  by  admitting  the  air  for  combus- 
tion in  small  enough  jets,  and  deflecting  the  currents  of  smoke  and  gases 
so  as  to  cause  them  to  mingle  with  the  air,  the  quantity  required  for  dilu- 
tion might  be  reduced  below  that  indicated  by  the  above  calculation. 
Undoubtedly  all  the  air  which  is  admitted  into  the  fire-box  which  does 
not  combine  with  the  chemical  elements  of  the  fuel  lessens  the  amount  of 
steam  generated  in  the  boiler,  both  with  reference  to  time — that  is  to  say, 
per  minute — and  to  fuel — that  is,  per  pound  of  coal  consumed.  But  with 
the  present  locomotive  boiler  it  is  simply  a choice  of  two  evils.  If  no 
more  air  is  admitted  than  theory  indicates  to  be  needed  for  combustion, 

* Rankine.  In  a paper  read  before  the  Chemical  Society  of  Paris  by  M.  Scheurer-Kestner, 
he  reported  that  in  some  experiments  made  to  determine  the  quantity  of  air  most  favorable  to 
combustion  that  of  the  furnace  was  fed  with  a volume  of  air  about  5 per  cent,  more  than  the 
theoretical  quantity  required  for  combustion. 


568 


Catechism  of  the  Locomotive. 


then,  owing  to  the  imperfect  means  which  are  usually  employed  to  cause 
the  air  and  fuel  to  combine,  a portion  of  the  latter  will  escape  unconsumed  ; 
and  if  more  air  is  admitted,  the  temperature  of  the  products  of  combustion 
is  lowered  and  their  volume  increased,  the  evils  of  which  have  already 
been  pointed  out.  It  therefore  becomes  a matter  in  which  we  are  obliged 
to  consult  experience  and  determine  by  experiment  what  amount  of  air 
it  is  necessary  to  admit  to  the  fuel  to  produce  the  most  economical 
results. 

Question  746.  What  proportion  of  the  air  should  be  admitted  through 
the  grate,  and  how  much  above  the  fire? 

Answer.  This,  too,  is  a question  which  can  probably  be  answered  best 
by  consulting  experience.  The  relative  quantity  of  air  required  above  and 
below  the  fire  depends  very  much  on  the  nature  of  the  fuel.  Coal  which 
“runs  together”  or  cakes  very  much  or  has  a great  deal  of  clinker  in  it, 
doubtless,  will  need  more  air  above  the  fire  than  other  coal  which  is  said  to  be 
“drier,”  for  the  reason  that  it  will  be  found  impossible  to  admit  so  much 
air  through  the  caking  coal  in  the  grate  as  through  the  other  kind.  An 
idea  of  the  relative  quantity  which  should  be  admitted  above  and  below 
the  fire  may  be  found  if  we  know  how  much  air  is  needed  to  burn  the 
solid  carbon  or  coke  which  is  left  after  the  gas  is  expelled  from  it,  and 
how  much  for  the  gas  itself.  The  gas  which  is  expelled  from  a pound  of 
coal  consists  of  about  0.05  lb.  of  hydrogen  and  0.15  lb.  of  carbon.  Now,  it 
has  been  show  that  hydrogen  requires  36  times  its  weight  of  air  to  burn  it 
perfectly,  so  that  0.05  lb.  would  need  0.05  x 36  = 1.8  lbs.;  and  carbon  requires 
12  times  its  weight  of  air,  so  that  for  0.15  lb.  of  carbon  0.15  x 12=1.8  lbs. 
is  needed,  so  that  for  both  3.6  lbs.  of  air  is  required  for  perfect  combus- 
tion. As  has  been  shown,  12  lbs.  is  needed  to  consume  the  whole  of  the 
fuel,  so  that  30  per  cent,  of  the  whole  supply  is  required  for  the  combus- 
tion of  the  gas  alone.  If  this  is  diluted  in  the  same  proportion  as  that 
required  for  the  combustion  of  the  carbon,  and  it  probably  should  be  even 
more  so,  we  would  have  30  percent,  of  225=67.5  cubic  feet  of  air  required 
for  the  combustion' of  the  gas.  It  is  certain,  however,  that  the  solid  coke 
on  the  grates  is  not  perfectly  consumed,  or,  in  other  words,  converted  into 
carbonic  dioxdide,  especially  when  the  layer  of  it  on  the  grates  is  very 
thick.  When  this  is  the  case  the  air  coming  in  contact  with  the  lower 
layer  of  coke  forms  carbonic  dioxide,  but  as  it  rises  through  the  burning 
coke  another  equivalent  of  carbon  unites  with  the  carbonic  dioxide,  and 
thus  forms  carbonic  oxide.  If,  now,  enough  air  is  admitted  above  the  fire, 
this  carbonic  oxide  will  combine  with  it,  and,  as  has  been  explained  before. 


Combustion. 


569 


a second  conbustion  will  take  place  if  there  is  time  and  opportunity  for 
combination  before  the  gases  enter  the  flues.  It  is  therefore  probable 
that  more  than  30  per  cent,  of  the  whole  supply  of  air  should  be  admitted 
above  the  fire.  It  is  at  any  rate  best  to  provide  the  means  for  admitting 
more,  and  also  appliances  for  regulating  the  supply,  so  that  it  can  be 
governed  as  experience  may  indicate  to  be  best. 

Question  747.  Is  it  not  possible  by  enlarging  the  grate  to  admit  enough 
air  to  the  fire  to  produce  perfect  combustion  ? 

Answer.  Yes;  when  no  air  is  admitted  above  the  fire,  large  grates  are 
found  to  produce  the  best  combustion.  But  while  it  is  true  that  the  same 
amount  of  heat  will  be  produced  by  the  union  of  each  equivalent  of 
oxygen  and  fuel,  yet  if  we  can  force  more  air  and  fuel  to  unite  in  the  same 
place,  a higher  temperature  is  produced  in  that  place,  just  as  a fire  in  a 
blacksmith’s  forge  is  hotter  because  of  the  forced  blast  than  that  in  an 
ordinary  stove,  or  a smelting  furnace  than  a parlor  grate.  If,  then,  we 
can  concentrate  the  draft  in  the  fire  of  a locomotive,  we  secure  a greater 
intensity  of  combustion ; and  when  the  air  is  urged  against  the  solid  carbon 
with  considerable  force  it  comes  in  contact  with  every  point  of  its  surface, 
and  therefore  less  dilution  of  the  air  is  needed,  and  consequently  the 
products  of  combustion  have  a higher  temperature,  and,  as  has  been  ex- 
plained, a larger  proportion  of  the  heat  is  then  transferred  to  the  water 
than  if  the  temperature  is  lower  and  the  volume  greater. 

Intensity  of  combustion  also  has  the  effect  of  maintaining  an  igniting 
temperature ; whereas,  if  the  same  amount  of  fuel  is  burned  slowly,  its 
heat  may  not  be  high  enough  to  ignite  the  gases  as  they  are  produced. 

It  is  desirable,  however,  to  have  all  the  space  that  is  possible  in  the  fire- 
box, so  as  to  give  room  for  the  mixing  of  the  gases ; but  with  a large  fire- 
box and  large  grate  a decided  improvement  and  economy  will  often  result 
by  diminishing  the  effective  area  of  the  grate  by  covering  a part  of  it  with 
dead-plates,  but  at  the  same  time  making  provision  for  the  admission  of 
air  above  the  fire. 

Question  748.  What  is  meant  by  the  “ Total  Heat  of  Combustion  ? ” 

Answer.  It  is  the  number  of  units  of  heat  given  out  by  the  combustion 
of  a given  quantity  (usually  a pound)  of  fuel. 

Question  749.  How  is  this  determined? 

Answer.  The  heat  given  out  by  the  combustion  of  1 lb.  of  the  chemical 
elements  of  which  coal  is  composed  has  been  determined  by  experiment, 
and  from  such  data,  knowing  the  substances  of  which  fuel  is  composed, 
we  can  determine  the  amount  of  heat  which  would  be  developed  if  they 


570 


Catechism  of  the  Locomotive. 


were  each  perfectly  consumed.  Thus  the  total  heat  of  combustion  of  1 
lb.  of  hydrogen  is  62,032  units,  and  of  the  same  quantity  of  carbon  14,500 
units.*  Therefore,  if  a pound  of  coal  contains  5 per  cent,  of  hydrogen, 
the  heat  given  out  by  the  combustion  of  that  element  will  be  62,032  x 0.05 
=3,101.60  units,  and  if  it  has  80  per  cent,  of  carbon,  the  combustion  of  the 
latter  would  develop  14,500  x 0.80=11,600  units,  so  that  the  total  heat  of 
the  combustion  of  these  two  elements  would  be  3,101.6  + 11,600=14,701.6 
units.  It  was  shown  in  answer  to  Question  84  that  it  required  1,213.4 
units  of  heat  to  convert  water  at  zero  to  steam  of  100  lbs.  pressure.  As 
steam  is  usually  generated  from  water  at  a temperature  of  about  60°,  the 
total  heat  required  to  convert  it  into  steam  of  100  lbs.  pressure  would  be 
1,213.4—60  = 1,153.4  units.  A pound  of  average  bituminous  coal,  there- 
fore, contains  heat  enough  to  convert  12£  lbs.  of  water  of  60°  temperature 
into  steam  of  100  lbs.  absolute  pressure.  Ordinarily  only  about  half  that 
amount  of  water  is  evaporated  in  locomotive  boilers  per  pound  of  fuel. 
Question  750.  What  are  the  chief  causes  of  this  waste  of  heat? 
Answer.  It  is  due,  first,  to  the  waste  of  unburned  fuel  in  the  solid  state. 
This  occurs  when  fuel  which  is  very  fine  falls  through  the  grates,  or  is 
carried  through  the  tubes  and  out  of  the  chimney  in  the  form  of  cinders.f 
Second,  to  the  waste  of  unburned  fuel  in  the  gaseous  or  smoky  state. 
The  method  of  preventing  this  waste  by  a sufficient  supply  and  proper 
distribution  of  air  has  been  explained  in  the  answer  to  preceding  questions. 
The  quantity  of  heat  wasted  by  smoke  is,  however,  much  smaller  than  is 
ordinarily  supposed.  Experiments  have  shown  that  however  black  and 
thick  it  may  be,  it  does  not  exceed  1^  per  cent,  of  the  carbon  in  the  coal 
and  if  air  enters  the  fire  freely  the  loss  falls  to  -J  per  cent.J 

Third,  to  the  waste  or  loss  of  heat  in  the  hot  gases  which  escape  up  the 
chimney  or  smoke-stack.  The  temperature  of  the  fire  in  a locomotive 
fire-box  in  a state  of  active  combustion  is  probably  from  3,000  to  4,000°. 
This  heat  is  in  part  radiated  and  conducted  to  the  heating  surface  of  the 
fire-box,  and  it  is  found  that  more  water  is  evaporated  by  this  portion  of 
the  heating  surface  in  proportion  to  its  area  than  by  any  other  in  the 
boiler.  The  gases  when  they  enter  the  tubes  transmit  a portion  of  their 
heat  to  the  surfaces  with  which  they  are  first  in  contact.  The  amount  of 

* The  experiments  which  have  been  made  to  determine  these  amounts  do  not  agree  exactly, 
but  those  given  are  thought  to  be  the  most  trustworthy. 

t It  should  be  remarked  here  that  some,  and  perhaps  many,  of  the  cinders  which  are  carried 
out  of  the  chimney  are  not  combustible,  but  are  composed  of  the  same  materials  that  form 
clinkers  on  the  grate. 

X See  paper  read  by  M.  Scheurer-Kestner  before  the  Chemical  Society  of  Paris. 


Combustion. 


571 


heat  thus  transmitted,  as  has  been  stated,  is  in  proportion  to  the  difference 
in  temperature  of  the  gases  inside  the  tubes  and  that  of  the  water  outside. 
After  passing  over  the  part  of  the  tube  with  which  the  gases  are  first  in 
contact,  they  then  arrive  at  another  portion  of  the  tube  surface  with  a 
diminished  temperature,  and  the  rate  of  conduction  is  therefore  dimin- 
ished, so  that  each  successive  equal  portion  of  the  heating  surface  trans- 
mits a less  and  less  quantity  of  heat,  until  the  hot  air  at  last  leaves  the 
heating  surface  and  escapes  up  the  chimney  with  a certain  remaining 
excess  of  temperature  above  that  of  the  water  in  the  boiler,  the  heat  cor- 
responding to  which  excess  is  wasted.*  It  is,  therefore,  desirable  to 
extract  as  much  heat  as  possible  from  the  gases  before  they  escape  from 
the  tubes.  Now  it  will  be  impossible  to  heat  the  water  outside  of  the 
tubes  hotter  than  the  gases  inside.  When  the  temperature  of  the  water 
is  equal  to  that  of  the  gases,  no  more  heat  will  be  transmitted  from  one 
to  the  other.  If  the  temperature  of  the  water  is  350° , that  of  the  gases  in 
the  tubes  will  never  be  any  lower,  but  will  escape  into  the  smoke-box  with 
not  less,  but  usually  considerably  more,  than  that  amount  of  heat.  If, 
however,  the  cold  water  is  introduced  at  the  front  end  of  the  tubes,  so 
that  the  surface  with  which  the  gases  are  last  in  contact  has  a temperature 
considerably  lower  than  350,  then  an  additional  amount  of  heat  will  be 
transmitted  before  they  escape.  It  is,  therefore,  important  that  the  cold 
feed-water  should  be  admitted  near  the  front  end  of  the  boiler,  so  that  the 
products  of  combustion  will  be  in  contact  with  the  coldest  part  of  the 
heating  surface  last,  and  thus  give  out  as  much  of  their  heat  as  possible 
before  they  escape.  As  a matter  of  fact,  the  gases  escape  at  a much 
higher  temperature.  Experiments  made  by  the  writer  showed  that  the 
temperature  in  the  smoke-box  of  a locomotive  when  first  starting  was 
270°,  and  when  working  at  its  maximum  capacity  on  a steep  grade  and 
with  a heavy  train  it  was  as  high  as  675°.  The  average  temperature  while 
running  was,  in  three  trials  on  different  parts  of  the  road,  as  follows  : 

Average  steam  pressure,  98.8  lbs. ; average  temperature,  499.8  lbs. 

Average  steam  pressure,  106  lbs. ; average  temperature,  535.1  lbs. 

Average  steam  pressure,  112.2  lbs. ; average  temperature,  554  lbs. 

In  making  these  experiments  a record  was  made  of  the  indications  of  a 
pyrometer  and  of  the  steam  gauge  once  every  minute  while  the  engine 
was  running.  The  distance  run  was  19  miles  for  the  first  experiment,  13 
for  the  second,  and  6 for  the  third,  with  30  loaded  freight  cars  in  the  train. 


* Rankine. 


572 


Catechism  of  the  Locomotive. 


The  last  experiment  was  made  while  the  engine  was  working  on  a heavy 
grade  and  very  nearly  up  to  its  maximum  capacity. 

It  will  thus  be  seen  that  a great  deal  of  heat  is  wasted  by  escaping  up 
the  chimney. 


Fourth,  by  external  radiation  from  the  boiler.  This  occurs  chiefly  from 
the  fact  that  it  is  not  sufficiently  well  protected  or  covered  with  non- 
conducting material.  The  practice,  or  rather  the  neglect,  of  not  covering 


Combustion. 


573 


the  outside  of  the  fire-box  with  lagging  doubtless  causes  a very  consider- 
able loss  of  heat  by  radiation  and  convection  from  the  hot  boiler  plates. 

Question  751.  What  is  the  ordinary  form  of  fire-box  employed  for 
burning  bituminous  coal  f 


Fig.  471.  Transverse  Section  of  Fire-Box  with  Brick  Arch.  Scale  % in.=l  ft. 


Answer.  It  is  that  represented  in  Plate  IV  and  figs.  121-123,  and  is 
simply  a rectangular  box,  and  for  that  reason  it  is  often  called  a plain 
fire-box.  Sometimes  provision  is  made  for  admitting  air  into  such  fire- 


574 


Catechism  of  the  Locomotive. 


boxes  through  hollow  or  rather  tubular  stay-bolts,  which  are  put  into  the 
sides  and  front.  In  most  cases,  too,  the  fire-box  door  has  openings  for 
admitting  air. 

Question  752.  What  other  appliances  are  used for  burning  bituminous 
coal? 

Answer.  The  most  common  appliances  which  are  added  to  the  plain 
fife-box  are  what  are  called  fire-brick  arches  or  deflectors.  These  are  some- 
times made  of  an  arched  form,  and  rest  on  supports  on  the  sides  of  the 
fire-box.  In  other  cases  the  fire-brick,  F F,  figs.  470  and  471,  is  supported 
on  tubes,  T T,  which  are  fastened  to  the  front  and  back  ends  of  the  fire- 
box or  into  the  crown-sheet.  These  tubes  permit  the  water  in  the  boiler 
to  circulate  through  them,  which  prevents  them  from  being  burned  by  the 
intense  heat  in  the  fire-box.  The  fire-brick  deflector  extends  backward 
and  upward  from  a point  on  the  tube  sheet  a short  distance  below  the 
tubes.  A space,  A,  between  the  top  of  the  deflector  and  the  crown-sheet 
is  left  open,  so  that  the  smoke  and  gases  from  the  fire  must  pass  under  the 
deflector  and  around  and  over  its  back  end,  as  indicated  by  the  arrows  in 
fig.  470.  In  this  way  the  products  of  combustion  are  delayed  in  the  fire- 
box before  they  enter  the  tubes,  which  gives  time  for  the  gases  and  air  to 
combine  and  combustion  to  take  place.  The  fire-brick  becomes  heated, 
and  thus  to  some  extent  prevents  the  gases  from  being  cooled  down  below 
an  igniting  temperature  by  contact  with  the  cold  surface  of  the  fire-box 
before  combustion  is  complete.  The  fire-brick,  however,  soon  burns  out, 
and  must  often  be  replaced,  but  owing  to  its  cheapness  and  the  ease  with 
which  it  can  be  removed,  this  is  not  a very  serious  objection  to  its  use. 
Air  is  nearly  always  admitted  above  the  fire  when  the  brick  arch  is  used, 
either  by  tubular  stay-bolts  or  perforations  in  the  door,  or  both.  The 
tubes,  T T,  are  fastened  in  the  front  and  top  or  back  plates  of  the  fire- 
box by  caulking. 

When  air  is  admitted  at  the  furnace  door  of  an  ordinary  fire-box,  it  is 
very  apt  to  rush  directly  into  the  tubes  without  mingling  with  the  gases. 
It  was  found  by  some  of  the  firemen  on  English  railroads  that  by  placing 
an  inverted  shovel  in  the  top  of  the  furnace  door  opening,  the  current  of 
air  which  entered  could  thus  be  deflected  downward,  and  in  this  way 
smoke  could  be  almost  entirely  prevented.  This  led  to  the  adoption  of  a 
hood  or  deflector,  A,  fig.  472,  which  is  made  of  sheet  iron  and  is  placed 
over  the  fire-box  door  and  is  arranged  with  a lever,  B , so  that  it  can  be 
raised  in  order  to  be  out  of  the  way  when  coal  is  thrown  on  the  fire.  It  is 
suspended  from  a hook,  C,  from  which  it  can  easily  be  detached  and  taken 


Combustion. 


575 


out  for  repairs.  This  is  frequently  necessary,  as  the  intense  heat  of  the 
fire-box  burns  away  the  sheet  iron,  of  which  it  is  made,  very  rapidly.  It 
can  be  made  of  old  boiler  plate,  so  that  the  expense  of  renewal  is  very 


Fig.  472.  Section  of  Fire-Box  with  Deflecting  Plate  over  Door.  Scale  % in.=l  ft. 


slight.  When  this  plan  is  used,  a double  sliding  door,  shown  in  fig.  473, 
is  commonly  used  with  it.  These  doors  are  opened  by  the  levers,/ dg 
and  e h,  which  are  connected  together  by  the  rod,  r.  With  these  sliding 
doors  the  area  of  the  opening  for  the  admission  of  air  can  easily  be 
regulated. 

Figs.  474  and  475  represent  a furnace  door  used  on  an  English  railroad. 
The  door,  A,  is  hinged  so  as  to  open  inward.  It  is  opened  and  closed, 
and  its  position  can  be  adjusted  by  the  lever,  C.  B is  a door  hinged  at 


576 


Catechism  of  the  Locomotive. 


the  bottom  to  protect  the  fireman  from  the  heat  of  the  fire.  By  leaving 
the  door,  A,  partly  open  air  is  admitted  and  deflected  downward  on  the 
fire  for  the  reason  already  described. 


Fig.  473.  Double  Furnace  Door.  Scale  % in.=l  ft. 


On  the  New  York  Central  & Hudson  River  Railroad  the  form  of  fire- 
box, shown  in  figs.  476-478,  which  was  designed  by  Mr.  William  Buchanan, 
Superintendent  of  Machinery  of  that  line,  is  used  quite  extensively,  and 
avoids  the  inconvenience  and  expense  of  frequently  replacing  the  fire- 
brick and  gives  very  perfect  combustion.  This  consists  of  what  is  called 


English  Furnace  Door.  Scale  % in.=l  ft. 


a water-table,  A A,  fig.  476 — that  is,  two  plates  with  water  between  them 
similar  to  the  sides  of  the  fire-box.  This  extends  completely  across  the 
fire-box  from  the  tube-sheet  to  the  back-plate,  thus  dividing  the  fire-box 
into  two  compartments,  M and  N.  In  order  to  afford  communication 
from  the  lower  one  to  the  upper  one  a round  hole,  D,  about  18  inches  in 


Fig.  476. 


578 


Catechism  of  the  Locomotive. 


diameter,  is  put  in  the  water-table  in  the  position  shown.  It  will  thus  be 
seen  that  all  the  currents  of  gas,  smoke,  and  air  must  unite  in  passing 


through  this  opening,  and  are  thus  brought  into  close  contact  with  each 
other.  After  they  enter  the  upper  chamber  and  before  they  enter  the 
tubes,  there  is  room  and  time  for  combustion.  For  the  purpose  of  supply- 
ing fresh  air  above  the  fire,  Mr.  Buchanan  puts  four  tubes,  AAA  A — 
shown  in  an  enlarged  scale  in  figs.  479  and  480 — in  the  front  end  and  an 
equal  number  in  the  back  end  of  the  fire-box  just  above  the  fire.  These 


Combustion. 


579 


tubes  each  have  a cone,  C,  fig.  479,  inside  of  it,  which  has  an  annular  open- 
ing or  space,  D D,  around  it.  The  cone  is  held  in  position  by  the  ribs,  E E, 
fig.  480,  which  are  attached  to  it.  Each  of  these  tubes  has  a steam  nozzle,  n 
n,  opposite  to  it.  Steam  is  conducted  to  these  nozzles  by  the  pipe,  F F — 
F,  the  supply  being  regulated  by  the  cock,  G,  fig.  478.  A jet  of  steam  can 
thus  be  discharged  into  each  one  of  the  tubes,  the  effect  of  which  is  to 
create  an  induced  current  of  air  into  the  tubes,  or,  in  other  words,  the 
steam  carries  a large  amount  of  air  into  the  tubes  with  it.  When  the 
steam  and  air  strike  the  cone,  C,  fig.  479,  it  deflects  or  spreads  them  as 
indicated  by  the  dotted  lines  which  diverge  from  the  nozzles  in  the  differ- 
ent figures.  The  effect  is  to  distribute  and  mix  the  air  with  the  gases  in 
the  fire-box,  and  thus  promote  combustion.  The  furnace  doors  of  these 
fire-boxes  also  have  deflectors,  H , and  movable  dampers,  /,  which  are 


swung  on  trunnions  so  that  their  position  can  be  adjusted  by  a latch,  L. 
The  air  can  thus  enter  the  fire-box  through  the  door,  and  is  deflected 
downward  as  indicated  by  the  arrows  in  fig.  476.  The  direction  of  the 
smoke  and  gases  is  indicated  by  the  arrows  which  show  how  they  come 
into  contact  in  passing  through  the  opening,  D,  in  the  water-table.  The 
steam  jets  and  the  furnace  door  furnish  the  means  of  supplying  an  abund- 
ance of  air  to  the  fire,  which  is  intimately  mixed  below  the  water-table 
and  in  passing  through  the  opening,  D,  with  the  gases  from  the  coal,  so 
.that  very  complete  combustion  results  in  the  chamber,  M. 

QUESTION  753.  How  do  the  plans  for  burning  coal  which  have  been 
described  operate  ? 

Answer.  They  will  all  burn  coal  more  perfectly,  and  therefore  more 
economically,  if  they  are  carefully  and  skilfully  managed,  than  is  possible 
in  ordinary  plain  fire-boxes  ; but  it  is  probable  that  as  much  economy  in 


580 


Catechism  of  the  Locomotive. 


the  consumption  of  coal  would  result  from  the  improvement  of  the  prac- 
tice and  knowledge  of  firemen  as  can  be  expected  from  the  use  of  any  of 
the  appliances  described,  if  they  are  used  without  care  or  knowledge  of 
the  principles  of  combustion. 

QUESTION  754.  In  what  respect  does  anthracite  coal  differ  from  bitu- 
minous ? 

Answer.  It  differs  chiefly  in  the  fact  that  it  contains  a much  larger 
proportion  of  carbon  and  less  of  hydrogen,  and  in  the  fact  that  it  conse- 


Fig.  481. 


Fig.  482. 

Water  Grate  for  Anthracite  Coal.  Scale  % in.=l  ft. 


quently  gives  off  very  little  or  no  coal  gas.  Its  combustion  is  therefore 
more  simple  than  that  of  bituminous  coal,  as  there  is  very  little  else  than 
solid  carbon  to  burn. 

Question  755.  In  what  kind  of  a fire-box  is  anthracite  usually  burned? 

Answer.  It  is  usually  burned  in  very  a long  grate,  figs.  481-483,  and 
as  the  heat  is  very  intense,  the  grate-bars,  £ B,  are  usually  made  of  iron 


Combustion. 


581 


tubes,  through  which  a current  of  water  circulates,  so  as  to  prevent  them 
from  melting.  These  tubes  are  screwed  into  the  front-plate  of  the  fire- 
box, and  are  fastened  with  tapered  thimbles  in  the  back  ends,  which  are 
driven  into  holes  in  the  back-plate  so  as  to  make  a tight  joint  around  the 
tube.  As  these  tubes  are  fastened  in  the  plates  and  are  immovable,  it  is 
essential  that  some  means  be  provided  for  drawing  the  fire  from  the  fire- 
box. This  is  done  by  using  solid  bars,  C C,  instead  of  tubes  at  intervals 
in  the  grate,  as  shown  in  figs.  481-483.  These  solid  bars  rest  on  a support 


( g > 


Fig.  483.  Water-Grate  for  Anthracite  Coal.  Scale  % in.=l  ft. 


or  bearing-bar,  D D,  as  it  is  called,  at  the  front  end,  and  pass  through 
tubes,  E E,  in  the  back  end  of  the  fire-box.  These  tubes  are  caulked  in 
each  plate  so  as  to  make  them  tight.  The  bars  have  eyes,  F E,  on  the 
ends  for  drawing  them  out  when  the  fire  must  be  removed. 

Question  756.  Is  it  important  to  admit  air  above  an  anthracite  coal 
fire  to  facilitate  combustion  ? 

Answer.  It  is  not  so  important  as  it  is  in  bituminous  coal,  but  if  the 
layer  of  anthracite  in  the  grates  is  very  thick,  it  will  be  impossible  to  get 
enough  air  through  the  coal  to  convert  all  the  carbon  into  carbonic 
dioxide,  and  the  carbon  and  oxygen  will  therefore  unite  so  as  to  form  car- 
bonic oxide.  If  air  is  admitted  above  the  fire,  as  has  already  been 
explained,  another  equivalent  of  oxygen  will  unite  with  the  carbonic 
oxide,  and  a second  combustion  will  then  take  place  above  the  fire,  and 
the  carbonic  oxide  will  thus  be  converted  into  carbonic  dioxide.  If,  under 
these  circumstances,  no  air  was  admitted  above  the  fire,  the  second  com- 
bustion would  not  occur,  and  all  the  heat  produced  thereby  would  be  lost. 

QUESTION  757.  In  what  way  is  combustion  influenced  by  the  arrange- 
ments in  the  smoke-box  of  the  locomotive  ? 

Answer.  The  draft  is  dependent  on  the  proportions,  location,  and  ad- 
justment of  the  blast  orifices  and  the  other  appliances  used  in  the  smoke- 
box.  The  smaller  the  blast  orifices  are  the  more  violent  will  be  the  escape 
of  steam  and  the  draft  of  air  through  the  fire.  But  the  draft  is  also 


582 


Catechism  of  the  Locomotive. 


dependent  on  the  arrangement  and  proportions  of  the  wire  netting,  deflec- 
tors, chimney,  and  other  appliances  used  in  the  smoke-box.  No  exact 
rules  can  be  given  for  the  arrangement  of  these  parts,  as  the  principles  of 
their  operation  are  still  very  imperfectly  understood.  The  best  arrange- 
ment for  them  must,  to  a very  great  extent,  be  determined  by  experiment. 


Fig.  484.  Longitudinal  Section  of  Extended  Smoke-Box  Front.  Used  on  the  New  York 
Central  and  Hudson  River  Railroad.  Scale  % in.=l  ft. 


Question  758.  What  is  an  extended  smoke-box  or  extended  front-end , 
and  what  is  it  for  ? 

Answer.  As  it  name  implies,  it  is  an  extension  of  the  smoke-box  in 
front  of  the  chimney,  and  its  object  is  to  give  room  for  wire  netting  and 
for  collecting  sparks  and  cinders.  Such  a smoke-box  is  shown  in  Plates 


Combustion. 


583 


III  and  IV,  and  also  in  figs.  484  and  485.  In  the  latter  figures,  A A are 
the  exhaust  orifices  or  nozzles,  B is  the  chimney,  C and  D are  deflectors  or 
plates  in  front  of  the  tubes.  The  deflector,  D,  has  a sliding  door,  G,  which 
is  moved  up  and  down  by  the  shaft,  S,  which  has  arms,  H and  /,  the  former 
connected  to  the  door  by  rods,  J /,  and  the  latter  by  another  rod,  K Ky 


with  the  cab.  E E is  wire  netting  which  has  an  opening  or  man-hole,  F, 
also  covered  with  netting,  which  can  be  removed  to  give  access  to  the 
exhaust  nozzles. 

The  purpose  of  the  movable  door  or  deflector,  G,  is  to  regulate  the  draft, 
the  direction  of  which  is  indicated  by  the  arrows. 


584 


Catechism  of  the  Locomotive. 


QUESTION  759.  How  does  an  extended  smoke-box  help  to  arrest  sparks 
and  cinders  ? 

Answer.  By  means  of  the  deflectors  the  sparks  are  thrown  forward 
into  the  extension  of  the  smoke-box  where  the  current  of  air  and  gases  is 
not  violent.  As  the  wire  netting  at  the  same  time  offers  some  obstruction 
to  the  movement  of  the  sparks,  they  are  deposited  in  the  extension  of  the 
smoke-box,  from  which  they  can  be  removed  by  means  of  the  pipe,  P, 
which  is  closed  by  a sliding  door,  L. 

QUESTION  760.  How  can  we  determine  the  relative  value  of  different 
kinds  of  fuel for  use  in  locomotives  ? 

Answer.  This  can  only  be  determined  satisfactorily  by  actual  experi- 
ment. The  chemical  composition,  excepting  so  far  as  it  indicates  the 
presence  of  deleterious  substances,  such  as  sulphur,  ashes,  clinkers,  etc., 
affords  but  little  assistance  in  determining  the  value  of  fuel.  Nearly  the 
same  quantities  of  elements  in  different  fuels  may  arrange  themselves, 
before  and  during  combustion,  so  as  to  produce  very  different  series  of 
compounds.  It  is  true  that  the  composition  of  coal  gives  us  some  indica- 
tion of  its  heat-producing  capacity , but  the  extent  to  which  that  capacity 
can  be  converted  into  actual  steam  in  locomotive  boilers  depends  to  a 
very  great  extent  upon  the  conditions  under  which  the  fuel  is  burned.  It 
should  also  be  remembered  that  the  rapidity  with  which  steam  can  be 
generated  is  a very  important  matter  in  locomotive  practice.  Whether  a 
heavy  freight  train  can  be  taken  up  a given  grade,  or  a fast  express  make 
time,  often  depends  upon  the  amount  of  steam  which  can  be  generated 
by  the  fuel  in  each  second  of  time  that  the  boiler  is  worked  to  its  maximum 
capacity.  Therefore  any  appliance  for  improving  combustion,  which 
reduces  the  quantity  of  steam  which  can  be  generated  by  the  boiler  in  a 
given  time,  is  quite  sure  to  fall  into  disuse  or  be  abandoned.  It  is  of 
course  often  necessary  to  adapt  the  appliances  for  burning  fuel  to  the  fuel 
itself ; and  when  a poor  quality  of  the  latter  must  be  used,  more  boiler 
capacity  must  be  given  than  is  needed  to  do  the  same  work  with  better 
fuel. 


CHAPTER  XXXI. 


THE  RESISTANCE  OF  TRAINS.* 

Question  761.  What  is  meant  by  the  resistance  of  trains  or  cars? 
Answer.  It  is  the  power  required  to  move  them  on  the  track.  Thus,  if  a 
rope,  fig.  486,  was  attached  to  a car  at  one  end,  and  the  other  passed  over 


a pulley,  a,  and  a sufficiently  heavy  weight,  W,  was  hung  on  the  end  of 
the  rope,  it  would  move  the  car.  The  weight,  W,  would  then  be  equal  to 
the  resistance  of  the  car. 

Question  762.  How  can  the  resistance  of  cars  under  different  circum- 
stances be  determined? 

Answer.  It  has  been  found  that  it  takes  a force  of  from  4 to  6 lbs.  per 
ton  (of  2,000  lbs.)  to  move  a car  slowly  on  a level  and  straight  track 
after  it  is  started.  That  is,  if  a car  weighs  20  tons,  and  a rope,  fig.  486,  is 
attached  to  it  at  one  end  and  the  other  passed  over  a pulley,  a,  with  a 
weight,  W,  suspended  to  it,  it  will  require  a weight  equal  to  20  x 6 = 120 
lbs.  to  keep  the  car  moving  slowly.  If  two  cars  of  the  above  weight  were 
coupled  together,  it  would  require  twice  120,  or  240  lbs.,  and  if  three  were 

* Since  1873,  when  the  above  chapter  was  written,  a considerable  number  of  experiments 
have  been  made  on  the  resistance  of  cars  and  trains,  and  much  has  been  written  on  the  subject, 
but  not  much  additional  light  has  been  thrown  on  it.  The  original  data  relating  to  this  subject 
are  therefore  retained,  although  the  resistances  of  cars  given  are  probably  too  high  rather  than 
too  low. 


586 


Catechism  of  the  Locomotive. 


attached  to  each  other,  three  times  120,  or  360  lbs.,  and  so  on.  In  other 
words,  MULTIPLYING  THE  TOTAL  WEIGHT  OF  THE  CARS  IN  TONS  (OF 
2,000  LBS.)  BY  6 WILL  GIVE  US  THEIR  RESISTANCE,  OR  THE  FORCE 
REQUIRED  TO  KEEP  THEM  MOVING  ON  A LEVEL  AND  STRAIGHT  TRACK 

at  A slow  speed  after  they  are  started.  The  resistance  is  repre- 
sented by  the  weight,  IV,  above,  and  the  locomotive  must  exert  a force 
equal  to  that  weight  to  keep  the  train  moving.  As  the  speed  increases 
the  resistance  increases,  as  is  shown  by  the  following  table.  It  should  be 
stated  here,  however,  that  our  knowledge  regarding  this  whole  subject  of 
the  resistance  of  American  cars  and  trains  is  exceedingly  inaccurate  and 
imperfect,  and  the  data  given  in  the  books  are  largely  based  on  experi- 
ments made  in  Europe,  with  cars  of  a different  construction  from  those 
used  here.  There  is  reason  for  believing,  however,  that  the  resistance  of 
American  cars  is  less  than  that  of  European  cars,  and  we  have  assumed  it 
to  be  6 lbs.  per  ton  on  a level  at  very  slow  speed,  which  is  less  than  the 
resistance  which  is  usually  given  ; but  the  following  figures  should  be 
regarded  merely  as  an  approximation  to  the  actual  facts,  of  which  we  are 
still  in  ignorance  : 


Velocity  of  trains  in  miles  per  hour. . . . 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

60 

70 

Resistance  on  straight  line  in  lbs.  per 
ton  (of  2,000  lbs.) 

6.1 

6.6 

7.3 

8.3 

9.6 

11.2 

13.1 

15.3 

17.8 

20.6 

27 

34.6 

Now,  if  we  want  to  get  the  resistance  at  30  miles  an  hour  of  a train  of  10 
cars  weighing  each  20  tons,  the  calculation  would  be  10  x 20  x 11^=2,250  lbs. 
This  will  give  the  resistance  on  a level  and  straight  track.  On  an  ascend- 
ing grade  the  resistance  is  greater  than  that  given  above,  because,  besides 
pulling  the  car  horizontally,  it  is  necessary  to  raise  it  vertically  a distance 
equal  to  the  ascent  of  the  grade.  Thus  if  we  have  a grade  with  a rise  of 
40  feet  in  a mile,  the  amount  of  energy  required  to  simply  raise  the  weight 
of  a car  would  be  equal  to  its  weight  in  pounds  multiplied  with  the  verti- 
cal height  of  the  ascent.  Thus,  supposing  a car  which  weighs  40,000  lbs. 
to  be  run  1 mile  on  a grade  of  40  feet  ascent  in  that  distance,  then  the 
energy  expended  in  simply  raising  the  car  will  be  equal  to  40,000x40= 
1,600,000  foot-pounds.  If  it  was  necessary  to  raise  that  weight  by  a 
direct  vertical  lift  or  pull,  it  would  require  a force  equal  to  or  a little 
greater  than  the  load  to  do  it.  But  in  pulling  a car  or  train  up  a grade, 
which  is  an  inclined  plane,  the  force,  which  is  the  locomotive,  instead  of 


The  Resistance  of  Trains. 


58' 


being  exerted  through  the  vertical  distance  is  exerted  through  the  hori- 
zontal distance,  which  in  this  case  is  1 mile,  or  5,280  feet.  Therefore,  if 
we  divide  the  number  of  foot-pounds  of  energy  required  by  the  distance 
through  which  the  power  is  exerted,  it  will  give  us  the  force  exerted 
through  one  foot.  That  is, 

1,600,000 

= 303.08  lbs. 

5,280 

The  resistance  due  to  the  ascent  alone  of  a train  on  a grade  or  incline  can 
therefore  be  calculated  by  multiplying  the  weight  of  the  train  in 

POUNDS  BY  THE  ASCENT  IN  ANY  GIVEN  DISTANCE  IN  FEET  AND  DIVID- 
ING THE  PRODUCT  BY  THE  HORIZONTAL  DISTANCE  IN  FEET.  Thus  in  the 
above  example  the  rate  of  the  ascent  is  given  in  so  many  feet  per  mile; 
we  therefore  multiply  by  40  and  divide  by  5,280,  which  is  the  number  of 
feet  in  a mile.  If  the  rate  of  the  gradient  had  been  given,  as  it  sometimes 
is,  as  1 in  132,  we  would  simply  have  divided  the  weight  of  the  train  by 
the  latter  number.  If  we  want  to  get  the  resistance  per  ton  of  train  we 
substitute  for  its  weight  that  of  1 ton  in  pounds ; thus : 

2,000x40 

= 15.1  lbs. 

5,280 

If,  now,  we  have  the  resistance  which  is  due  to  the  ascent  or  gravity  alone , 
we  must  add  to  this  the  resistance  on  a straight  and  level  track,  at  the 
speed  at  which  the  train  runs,  in  order  to  determine  the  total  resistance 
on  the  grade.  On  a level  road,  at  a speed  of  5 miles  per  hour,  it  would 
be  6.1  lbs.  per  ton,  so  that  on  a grade  of  40  feet  to  a mile  at  that  speed  the 
resistance  would  be  6.1  +15.1—21.2  lbs.  per  ton,  and  at  10  miles  it  would 
be  6.6  + 15.1=21.7  lbs.,  and  at  30  miles  per  hour  on  the  grade  the  resistance 
would  be  11.2  + 15.1=26.3  lbs.  per  ton.  To  get  the  total  resistance  on  a 
grade  for  any  speed,  we  add  the  resistance  for  that  speed  on  a 

STRAIGHT  AND  LEVEL  LINE  TO  THE  RESISTANCE  DUE  TO  THE  ASCENT 
alone.  The  resistances  for  various  rates  of  speed  and  grades  has  been 
calculated,  and  is  given  in  the  following  table  : 


TABLE  OF  RESISTANCES  OF  RAILROAD  TRAINS  WITH  DIFFERENT  GRADES  AND  SPEEDS. 


588 


Catechism  of  the  Locomotive. 


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TABLE  OF  RESISTANCES  OF  RAILROAD  TRAINS  WITH  DIFFERENT  GRADES  AND  SPEEDS. 


The  Resistance  of  Trains. 


589 


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590 


Catechism  of  the  Locomotive. 


The  top  horizontal  row  of  figures  of  the  table  gives  the  rates  of  speed. 
The  left  hand  vertical  row  gives  the  rise  of  grade  in  feet  per  mile.  The 
resistance  for  any  given  grade  and  speed  is  given  where  the  vertical  row 
of  figures  under  the  rate  of  speed  and  the  horizontal  row  opposite  the  rise 
of  the  grade  intersecUeach  other.  Thus,  for  a grade  of  30  feet  per  mile 
and  a speed  of  45  miles  per  hour,  we  follow  the  vertical  column  under  the 
45  downward,  and  the  horizontal  column  opposite  30  to  the  right,  and 
where  the  two  intersect  the  resistance,  29.1  lbs.,  is  given. 

Question  763.  What  effect  do  curves  have  on  the  resistance  of  trains? 

Answer.  They  increase  the  resistance,  but  in  what  proportion  or  to 
what  extent  is  not  known  accurately.  European  authorities  say  that  the 
resistance  is  increased,  over  what  it  would  be  in  a straight  and  level  line, 
about  1 per  cent,  for  every  degree*  of  the  curve  occupied  by  a train.  It  is 
probable,  however,  that  the  resistance  of  American  cars,  which  nearly  all 
have  double  trucks,  is  not  so  great  on  curves  as  that  of  European  cars, 
which  nearly  all  have  long  and  rigid  wheel-bases,  and  whose  wheels  there- 
fore cannot  adjust  themselves  so  easily  to  the  curvature  of  the  track  as 
they  can  when  the  American  system  of  double  trucks  is  used. 

QUESTION  764.  What  is  meant  here  by  a degree  of  a curve? 

Answer.  In  order  to  measure  circles,  they  are  all  supposed  to  be 
divided  into  360  equal  parts,  which  are  called  degrees.  One  degree  of  a 
curve  is  therefore  °f  a complete  circle.  If  a curve  has  a long  radius, 
one  degree  of  such  a curved  track  will  be  longer  than  one  degree  of  a 
curve  with  a short  radius,  but  each  will  have  the  same  amount  of  “ bend  ” 
or  curvature.  It  is  this  latter  which  increases  the  resistance  of  trains,  and 
the  greater  the  number  of  degrees  of  a curve  occupied  by  a train  of  cars, 
the  greater  will  be  the  “bend  ” of  the  track,  and  therefore  the  greater  the 
resistance. 

QUESTION  765.  In  what  other  sense  is  the  term  “ degree  ” used  in  describ- 
ing railroad  curves  ? 

Answer.  The  term  is  used  by  civil  engineers  to  designate  the  “ deflec- 
tion angle  ” of  a curve,  the  meaning  of  which  may  be  most  clearly  defined 
by  explaining  the  usual  method  of  laying  out  railroad  curves,  which  is  as 
follows  : To  lay  off  a curve,  beginning  from  B on  the  straight  line,  A D, 
fig.  487,  an  engineer  would  place  his  instrument  at  B and  lay  off  an  angle, 
D B s,  called  the  “ tangential  angle f and  then  measure  100  feet  on  the 

♦The  “ degree  ’’  of  a curve  here  means  part  of  a complete  circle.  The  term  is  not  used 
here  in  the  sense  in  which  it  is  employed  by  civil  engineers,  which  is  explained  in  answer  to 
Question  765, 


The  Resistance  of  Trains. 


591 


line,  B s,  and  s would  then  be  the  second  point  or  “ station  ” in  the  curve. 
From  j he  would  then  lay  off  an  angle,  m s t,  called  the  “ deflection  angle,” 
which  is  equal  to  twice  the  tangential  angle,  and  then  measure  100  feet  on 
the  line,  s t ; t will  then  be  the  third  point  or  station  in  the  curve.  From 
t another  deflection  angle,  n t ic,  is  again  laid  off,  and  100  feet  is  measured 
from  t to  u , which  gives  the  fourth  station,  u.  This  process  is  continued 


for  any  length  of  curve.  The  amount  of  curvature  depends,  of  course, 
upon  the  deflection  angle,  and  consequently  curves  as  designated  as  of  so 
many  degrees,  meaning  a curve  laid  down  with  deflection  angles  of  that 
many  degrees,  and  chords  of  100  feet  in  length.  The  deflection  angles  are 
expressed  in  degrees  and  minutes,  which  are  written  as  follows : 3°,  15', 
which  means  3 degrees  and  15  minutes.  The  following  table  gives  the 
radii  in  feet  of  curves  corresponding  to  different  deflector  angles : 


REFLECTION  ANGLE  AND  RADII  OF  CURVES. 


592 


Catechism  of  the  Locomotive. 


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DEFLECTION  ANGLE  AND  RADII  OF  CURVES. 


The  Resistance  of  Trains. 


59: 


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594 


Catechism  of  the  Locomotive. 


QUESTION  766.  What  other  causes  affect  the  resistance  of  trains? 

Answer.  The  condition  of  the  track  and  the  force* and  direction  of  the 
wind.  On  a rough  track  the  resistance  is  very  much  greater  than  on  a 
smooth  one,  and  in  a strong  head  wind  it  is  much  more  difficult  to  pull 
a train  than  in  calm  weather. 


CHAPTER  XXXII. 


PERFORMANCE  AND  COST  OF  OPERATING  LOCOMOTIVES. 

Question  767.  What  are  the  elements  of  cost  of  operating  locomotives  ? 

Answer.  They  are  (1)  the  cost  of  fuel : (2)  of  the  service  or  wages  of 
the  engineer  and  fireman;  (3)  of  lubricating  and  illuminating  oil,  waste, 
and  miscellaneous  supplies ; (4)  of  repairs  to  the  engine  and  tender,  and 
(5)  cleaning  and  watchmen. 

Question  768.  In  what  way  may  the  cost  of  operating  locomotives  be 
counted  and  compared? 

Answer.  The  cost  is  usually  counted  at  so  much  per  train  mile  or  per 
car  mile. 

Question  769.  What  is  the  usual  cost  of  these  items  of  expense  ? 

Answer.  The  cost  per  train  mile,  of  course,  varies  very  much  with  the 
loads  hauled,  the  speeds,  grades,  condition  of  the  road,  weather,  price  of 
coal,  etc.  The  following  table,  taken  from  one  of  the  monthly  perform- 
ance sheets  of  the  Lake  Shore  & Michigan  Southern  Railroad,  gives  the 
cost  per  train  mile  for  the  different  classes  of  trains  : 

COST  OF  LOCOMOTIVE  SERVICE. 


Cost  per  Train  Mile. 


Kind  of  Train. 

Fuel, 

Cents. 

Wages, 

Cents 

Oil, 

Waste, 

etc., 

Cents. 

Repairs, 

Cents. 

Cleaning 

and 

Watchman, 

Cents. 

Total, 

Cents. 

Passenger 

4.27 

6.61 

.05 

3.77 

.21 

14.91 

Freight 

6.43 

6.61 

.05 

3 33 

.21 

16.63 

Working 

2.86 

6.61 

.05 

2.03 

.21 

11.76 

Switching 

2.57 

6.61 

.05 

2.19 

.21 

11.63 

Average 

4.94 

6.61 

.05 

3.15 

.21 

14  96 

59G 


Catechism  of  the  Locomotive. 


The  Lake  Shore  line  has  no  very  steep  grades,  and  consequently  its 
engines  are  not  so  heavy  as  those  on  some  other  roads.  On  the  Pennsyl- 
vania road,  for  example,  which  has  steep  grades  and  heavy  engines,  the 
average  cost  of  repairs  in  1887  was  6.48  cents  per  train  mile  or  more  than 
double  that  on  the  Lake  Shore  line,  for  the  month  quoted. 

Question  770.  What  proportion  do  the  locomotive  expenses  bear  to  the 
total  cost  of  operating  a railroad  ? 

Answer.  In  1888,  on  the  Lake  Shore  Railroad,  the  expenses  named  in 
the  table  were  nearly  15  per  cent,  of  the  total  operating  expenses. 

Question  771.  How  m.uch  coal  is  consumed  per  mile  by  a locomotive 
and  tender  without  a train  ? 

Answer.  No  very  reliable  experiments  have  been  made  with  large 
engines  to  determine  this,  but  in  some  experiments  which  were  reported 
to  the  Master  Mechanics’  Association  in  1876,*  it  was  shown  that  the 
coal  consumed  in  running  an  engine  and  tender,  the  total  weight  of  which 
was  about  50  tons,  over  a road  without  a train  at  an  average  speed  of  between 
20  and  25  miles  per  hour,  was  from  18i  to  25^-  lbs.  of  coal  per  mile,  or  an 
average  of  21  lbs.  Experiments  with  an  English  engine  showed  a con- 
sumption of  12  lbs.  per  mile.  The  tests  reported  to  the  Master  Mechanics’ 
Association  were,  however,  made  with  western  coal,  which  is  not  of  so 
good  a quality  as  English  coal. 

Question  772.  How.  much  coal  do  locomotives  usually  consume  per  train 
mile  in  ordinary  service  ? 

Answer.  This,  too,  varies  within  very  wide  limits.  On  the  Lake  Shore 
line,  for  example,  the  consumption  for  the  year  1888  per  train  mile  was  70 
lbs.  On  the  Pennsylvania  road,  in  1887,  it  was  91.2  lbs.,  whereas  on  the 
Philadelphia  & Erie  line,  for  the  same  period,  it  was  105.4  lbs. 

Question  773.  How  much  coal  is  consumed  per  car  per  mile  ? 

Answer.  On  the  Pennsylvania  Railroad,  in  1887,  the  consumption  of 
coal  was  12.37  lbs.  per  passenger  car  per  mile,  and  the  average  number  of 
cars  per  train  was  4.89.  This  was  the  total  consumption  of  fuel  by  the 
locomotive  which  was  apportioned  to  the  cars  alone,  no  coal  being 
allowed  for  moving  the  engine  and  tender. 

In  the  same  year  the  consumption  of  coal  per  freight  car  per  mile  was 
5.03  lbs.  per  car  per  mile,  and  the  average  train  consisted  of  24.16  cars. 
On  the  Philadelphia  & Erie  Division,  which  is  a nearly  level  line,  the  coal 
consumed  was  only  3.18  lbs.  per  car  per  mile,  and  the  average  train  con- 
sisted of  38.78  cars.  The  consumption  of  coal  was  divided  among  the  cars 


* See  report  of  that  year,  page  14£. 


Performance  and  Cost  of  Operating  Locomotives.  597 

alone,  no  allowance  being  made  for  the  engine  and  tender.  The  monthly 
premium  sheets  of  the  Pennsylvania  Railroad  show  that  the  consumption 
of  coal,  if  apportioned  to  the  cars  alone,  varies  from  3.8  to  17  lbs.  per 
freight  car  per  mile,  and"  from  9 to  24  lbs.  for  passenger  cars.  These  fig- 
ures give  the  average  results  on  the  roads  named. 

The  following  report  of  experiments,  which  were  carefully  made  by  the 
writer,  will  give  the  performance  of  a locomotive  when  great  care  is  taken 
to  produce  good  results.  It  should  be  stated,  however,  that  the  engine 
with  which  these  experiments  were  made  had  been  in  service  18  months 
without  receiving  thorough  repairs,  and  that  the  boiler  at  times  primed 
badly,  so  that  the  rate  of  evaporation  of  water  per  pound  of  coal  is  not  a 
fair  indication  of  the  performance  of  the  engine  in  that  respect.  The 
coal  used  was  known  as  Brazil  coal,  from  Indiana,  and  in  order  to  com- 
pare the  performance  of  two  engines  only  lumps  of  coal  were  used,  so 
as  to  leave  no  room  for  question  regarding  the  relative  amount  of  fine 
coal  used  by  each  engine.  The  maximum  grades  on  the  road  on  which 
the  experiments  were  made  were  30  feet  per  mile,  and  the  total  ascent 
from  the  lowest  to  the  highest  point  on  the  road  was  374  feet. 

LOCOMOTIVE  EXPERIMENTS. 


1873. 

1873. 

1873. 

Date  of  experiment 

July  21. 

July  28. 

August  2. 

Number  of  miles  run 

145 

145 

145 

Number  of  cars  hauled 

41 

31 

41 

Total  weight  of  cars,  lbs 

1,497,240 

1,119,650 

1,508,860 

Total  amount  of  coal  burned,  lbs. . . . 

8,676 

5,102 

7,221 

Total  amount  of  water  consumed,  lbs. 

63,531 

45,719 

52,609 

Water  evaporated  per  lb.  of  coal,  lbs. 

7.32 

8.02 

7.04 

Miles  run  per  ton  (cf  2,000  lbs.)  of  coal. 

33.4 

50.8 

38.8 

Coal  consumed  per  car  per  mile,  lbs. 

1.45 

1.13 

1.21 

Average  speed,  including  stops,  miles. 

11.1 

13 

13.8 

QUESTION  774.  How  can  we  determine  the  speed  at  which 

an  engine  is 

running  ? 

Answer.  In  the  absence  of  any  special  instruments  for  the  purpose,  BY 
COUNTING  THE  NUMBER  OF  REVOLUTIONS  OF  THE  DRIVING-WHEELS  PER 
MINUTE,  THEN  MULTIPLYING  THE  LENGTH  OF  THEIR  CIRCUMFERENCE  IN 
INCHES  BY  THE  NUMBER  OF  THEIR  REVOLUTIONS  PER  MINUTE  AND  THE 
PRODUCT  BY  60,  AND  DIVIDING  THE  LAST  PRODUCT  BY  63,360.  THE 
QUOTIENT  WILL  BE  THE  SPEED  IN  MILES  PER  HOUR.  Thus,  supposing 
driving-wheels  which  are614  inches  in  diameter,  and  whose  circumference 
is  therefore  193.2  inches,  should  make  164  revolutions  per  minute,  then 
193.2  x 164  x 60-^63.360=30  miles  (nearly)  per  hour. 


CHAPTER  XXXIII. 


THE  CARE  AND  INSPECTION  OF  LOCOMOTIVES  WHILE  IN  THE  ENGINE 

HOUSE. 

QUESTION  775.  What  are  the  principal  divisions  of  the  work  of  operat- 
ing or  running  a locomotive  ? 

Answer.  They  are : 

1.  Inspection  and  lubrication — that  is,  an  examination  of  the  parts  to 
see  that  they  are  in  good  working  order,  and  the  application  of  oil  to  the 
journals  and  other  parts  subjected  to  wear. 

2.  Getting  up  steam  and  firing. 

3.  Setting  the  engine  in  motion  and  starting  the  locomotive  and  train. 

4.  Management  while  running. 

5.  Management  in  case  of  accident. 

6.  Stopping  the  engine  and  train. 

7.  Laying  up. 

8.  Cleaning  the  engine. 

Question  776.  When  should  a locojnotive  be  inspected? 

Answer.  It  should  be  inspected  after  it  has  finished  its  run,  and  when 
there  is  no  fire  in  the  fire-box  and  when  the  engine  is  cold,  so  that  the 
grates,  smoke-box,  chimney,  and  other  parts  can  be  examined.  The 
object  of  this  inspection  is  to  see  whether  any  repairs  are  needed  before 
the  next  run.  The  engine  should  again  be  inspected  before  making 
another  run,  to  see  whether  every  part  is  in  good  condition,  and  that  the 
repairs,  if  any  were  needed,  have  been  properly  made. 

QUESTION  777.  When  the  locomotive  is  first  inspectedt  what  should  be 
especially  observed  about  the  boiler  ? 

Answer.  In  the  first  place,  all  new  boilers  should  be  tested  by  pressure 
before  being  used,  and  all  boilers,  whether  new  or  old,  should  be 
tested  periodically.  The  oftener  the  better.  The  ways  of  applying 
the  pressure  test  are  : 

1.  The  cold  water  test — that  is,  by  filling  the  boiler  with  cold  water 
and  then  forcing  in  an  additional  quantity  with  a force-pump  so  as  to 
raise  the  pressure  to  that  at  which  it  is  intended  to  test  the  boiler. 


Care  and  Inspection  of  Locomotives. 


599 


2.  The  warm  water  test,  by  filling  the  boiler  entirely  full  of  cold  water 
and  then  kindling  a fire  in  the  grate,  so  as  to  warm  this  water.  As  water 
expands  about  in  rising  from  60  to  212°,  the  rise  in  temperature  will 
cause  a corresponding  increase  in  pressure  ; boilers  are  also  tested  with 
warm  water  by  forcing  it  into  them  with  an  injector,  which  receives  a 
supply  of  steam  from  another  boiler. 

3.  By  steam  pressure. 

If  the  latter  method  were  not  so  commonly  used,  it  would  seem  the 
height  of  madness  to  test  a boiler — which  is  neither  more  nor  less  than 
an  attempt  to  explode  it — in  the  shop  where  it  is  built  or  repaired,  and 
where  the  results  of  an  explosion  would  be  more  disastrous  and  fatal  than 
anywhere  else,  in  order  to  see  whether  it  will  explode  when  put  into  service 
on  the  line  of  the  road.  The  danger  of  explosion  is  also  increased  at  such 
times  by  hammering  and  caulking  at  leaky  rivets  and  joints.*  It  would 
seem,  therefore,  very  much  more  rational  to  test  boilers  first  by  hydraulic 
pressure.  For  a first  test  this  is  preferable,  because  cold  water  will  leak 
through  crevices  which  would  be  tight  when  the  boiler  is  heated,  so  that 
leaks  can  be  more  surely  detected  with  cold  than  with  warm  or  hot  water. 
It  is,  however,  doubtless  true  that  boilers  are  often  strained  much  more 
by  the  unequal  expansion  of  the  different  parts  than  by  the  actual  pressure. 
It  is,  therefore,  thought  that  after  the  hydraulic  test  has  been  applied  the 
second  or  warm  water  test  should  be  used.  This  can  be  easily  done,  as 
the  boiler  must  be  filled  full  of  water  for  the  first  test.  When  the  boiler 
is  subjected  to  the  test  pressure,  it  should  be  carefully  examined  to  see 
whether  any  indications  of  weakness  are  revealed.  Any  material  change 
of  form  or  any  very  irregular  change  of  pressure  is  indicative  of  weakness. 
The  flat  stayed  surfaces  should  be  carefully  examined  by  applying  a straight 
edge  to  them  before  and  after  they  are  subjected  to  pressure,  to  see 
whether  they  change  their  form  materially.  One  of  the  greatest  dangers 
and  most  common  accidents  to  locomotive  boilers,  as  has  been  pointed 
out  in  a previous  chapter,  is  the  breaking  of  stay-bolts,  to  detect  which,  a 
locomotive  engineer  and  master  mechanic  should  exercise  constant  vigil- 
ance. While  the  pressure  is  on,  the  outside  surface  of  the  boiler  should 
be  thoroughly  examined  with  slight  blows  of  a hammer,  which  will  often 
reveal  a flaw  in  the  metal  or  a defect  in  workmanship.  After  the  hy- 
draulic and  warm  water  tests  have  been  applied,  the  boiler  should  be 
emptied,  and  the  inside  examined  carefully,  to  see  whether  any  of  the 
stays  and  braces  have  been  broken  or  displaced  by  the  test.  After  this 


Wilson  on  Boiler  Construction. 


000 


Catechism  of  the  Locomotive. 


has  been  done,  and  not  until  then,  should  steam  be  generated  in  the  boiler. 
In  making  the  latter  test  it  would  doubtless  be  more  safe  to  employ  a pres- 
sure somewhat  lower  than  that  employed  with  the  cold  and  warm  water. 

There  is  great  diversity  of  opinion  regarding  the  maximum  pressure 
which  should  be  employed  in  testing  boilers.  It  is  doubtless  true  that  a 
weak  boiler  might  be  injured  and  thus  made  dangerous  by  subjecting  it 
to  a very  severe  pressure,  while  without  such  a test  it  would  have  been 
safe.  Recent  experiments  have  indicated,  however,  that  in  most  cases  the 
ultimate  strength  of  material  is  actually  increased  by  subjecting  it  to  a 
strain  which  even  exceeds  the  elastic  limit,  provided  such  a strain  is  im- 
posed only  a few  times.  Although  no  absolute  rule  can  be  given  to 
govern  all  such  cases,  it  is  thought  that  for  the  hydraulic  and  warm-water 
tests,  a pressure  about  50  per  cent,  greater  and  for  the  steam  test  25  per 
cent,  greater  than  the  maximum  working  pressure  should  be  employed. 

Before  old  boilers  are  tested,  they  should  be  very  carefully  examined, 
both  inside  and  outside,  to  see  whether  they  are  injuriously  corroded.  It 
is  to  be  regretted  that  the  insides  of  locomotive  boilers  are  usually  made 
so  difficult  of  access  that  it  is  impossible  to  discover  the  extent  and  the 
effects  of  corrosion  without  the  most  careful  examination.  This  is  not 
possible  without  getting  inside  of  the  boiler.  Whenever  this  can  be  done, 
a prudent  locomotive  engineer  should  use  the  opportunity  of  inspecting 
the  boiler  of  his  engine  himself,  and  not  depend  upon  the  boiler-makers 
who  are  employed  for  that  purpose.  He  should  remember  that  it  is  his 
life  and  not  theirs  which  is  exposed  to  danger  by  any  weakness  or  defect 
in  the  construction  of  the  boiler  of  the  locomotive  which  he  runs. 

Before  starting  the  fire  in  a locomotive,  the  fire-box  should  be  carefully 
examined  to  see  if'  there  are  any  indications  of  leaks,  which  will  often 
reveal  cracked  plates,  defective  stay-bolts  or  flues.  If  the  latter  simply 
leak  at  the  joints,  they  can  generally  be  made  tight  by  caulking  or  by  the 
use  of  a tube  expander.  This  is  easily  done  when  the  engine  is  cold,  but 
if  not  attended  to  may  be  very  troublesome  on  the  road.  Bran  or  other 
substances  containing  starch,  mixed  with  the  feed  water,  may  stop  leaks, 
but  this  is  only  a temporary  expedient.  Leaks  of  the  boiler  should  always 
be  causes  for  suspicion,  and  a leaky  seam  or  stay-bolt  may  be  caused  by 
dangerous  internal  corrosion.  A leak  about  the  boiler  head  should  lead 
to  an  examination,  to  ascertain  whether  any  of  the  inside  stays  or  braces 
are  broken.  If  this  occurs  it  may  be  indicated  by  the  bulging  of  the  plate 
which  forms  the  boiler  head.  Leaks  at  other  parts  of  the  boiler  should 
be  examined,  as  they  may  reveal  dangerous  fractures. 


Care  and  Inspection  of  Locomotives. 


601 


It  is  of  the  utmost  importance,  both  for  safety  and  for  economy  of 
working,  that  boilers  should  be  kept  clean — that  is,  free  from  mud  and 
incrustation.  In  some  sections  of  the  country,  especially  in  the  Western 
States,  this  is  the  greatest  evil  against  which  locomotive  engineers  and 
those  having  the  care  of  locomotives  must  contend.  The  cures  which 
have  been  proposed  are  numberless,  but  that  which  is  now  chiefly  relied 
upon  is,  first,  the  use  of  the  best  water  that  can  be  procured,  and  second, 
frequent  and  thorough  washing  out  of  the  boiler. 

QUESTION  778.  How  can  defects , such  as  cracked  plates  or  dangerous 
corrosion,  be  discovered  in  a locomotive  boiler  ? 

Answer.  Such  defects  are  usually  indicated  by  leakage  while  the  engine 
is  in  service.  They  are  shown  by  a little  water  or  steam  oozing  at  the 
point  where  the  defect  exists.  When  the  engine  is  cold  a slight  collection 
of  incrustation  or  rust  on  the  outside  of  the  boiler  will  show  that  there 
has  been  a leak.  A*  defect  in  the  fire-box  will  often  be  shown  by  a leak 
at  the  mud-ring.  When  a fire-box  plate  is  cracked  it  usually  opens  sud- 
denly, so  that  the  leak  shows  at  once.  Tubes  are  liable  to  leak  when  there 
is  no  other  defect  excepting  that  they  need  caulking,  but  when  this  is 
done  the  tube-plate  should  always  be  examined  to  see  whether  it  is 
cracked. 

Question  779.  How  can  internal  corrosion  or  grooving  be  discovered? 

Answer.  Unless  it  has  become  so  serious  as  to  cause  an  external  leak, 
this  cannot  be  discovered  excepting  by  an  internal  inspection  of  the  boiler. 
To  do  this  the  dome-cover  must  be  taken  off  and  a person  must  go  inside 
of  the  boiler  and  examine  carefully  every  part  that  is  accessible.  To  make 
an  internal  inspection  thorough  the  tubes  must  be  taken  out.  When 
water  is  of  a corrosive  character,  or  contains  much  solid  matter  which  is 
deposited  inside  of  the  boiler,  such  an  inspection  should  be  made  fre- 
quently, but  when  the  water  is  pure  it  is  not  essential  to  do  it  often. 

QUESTION  780.  How  can  defects  in  braces  or  stays  or  broke7i  stay-bolts 
be  discovered? 

Answer.  Broken  braces  and  stay-bolts  are.  indicated  sometimes  by  the 
bulging  of  the  plates  of  the  flat  parts  of  the  boiler.  Broken  stay-bolts 
may  often  be  discovered  by  an  expert  by  sounding  them  with  a hammer, 
and  if  their  ends  are  drilled,  as  explained  in  answer  to  Question  228,  their 
fracture  is  shown  by  the  leakage.  An  internal  inspection  is  the  only  way 
of  being  sure  that  the  braces  are  in  good  condition. 

QUESTION  781.  What  must  be  done  to  prevent  the  inside  of  the  boiler 
and  the  tubes  from  becoming  covered  with  incrustation  ? 


602 


Catechism  of  the  Locomotive. 


Answer.  The  first  and  most  effective  preventative  is  to  get  the  purest 
water  that  is  obtainable  for  use  in  the  boilers.  Having  done  this,  if  it 
contains  much  solid  matter,  the  boiler  must  be  blown  out  and  washed  out 
often.  If  the  water  forms  a solid  deposit  it  will  be  necessary  to  take  out 
the  tubes  and  crown-bars  at  intervals,  and  clean  them  and  the  inside  of 
the  boiler  thoroughly. 

Question  782.  How  often  should  the  tubes  be  cleaned? 

Answer.  That  depends  very  much  upon  the  kind  of  fuel  used,  as  some 
coal  fills  up  the  tubes  much  more  than  other  kinds  do.  Every  time  the 
engine  is  washed  out  the  tubes  should  be  thoroughly  cleaned.  If  the  fuel 
used  leaves  considerable  deposit  in  the  flues,  it  is  well  to  brush  them  out 
as  thoroughly  as  is  possible  from  the  furnace  door. 

Question  788.  What  should  be  observed  with  reference  to  the  smoke-box  ? 

Answer.  It  should  be  noticed  whether  the  front  and  door  are  securely 
fastened  so  as  to  be  air-tight.  If  air  leaks  into  the  smoke-box  the  sparks 
or  cinders  are  liable  to  take  fire  on  the  inside  of  it,  which  heats  all  the 
parts  about  it,  blisters  the  paint  outside,  may  cause  the  steam  and  exhaust- 
pipes  to  leak,  and  destroy  the  wire  netting.  The  smoke-box  door  should 
be  opened  occasionally  to  see  whether  the  petticoat-pipe,  deflecting-plates, 
and  wire  netting  are  in  good  condition  and  properly  secured,  as  a failure 
of  any  of  these  parts  when  the  engine  is  on  the  road  is  very  annoying  and 
is  liable  to  cause  much  delay.  The  smoke-box  should  be  kept  clear  of 
ashes  and  cinders. 

QUESTION  784.  What  may  happen  to  the  convey  or  exhaust-pipes? 

Answer.  They  may  get  loose  or  may  require  adjusting.  Moving  them 
up  or  down  has  an  important  influence  on  the  draft,  but  experience  is  the 
best  teacher  with  reference  to  their  adjustment. 

Question  785.  What  may  happen  to  the  wire  netting  in  the  smoke-box 
or  in  the  top  of  the  chimney? 

Answer.  As  the  wire  netting  on  the  smoke-stack  often  has  holes  worn 
into  it  by  the  action  of  the  sparks,  it  should  be  frequently  examined  to  see 
whether  it  is  in  good  condition.  As  soon  as  holes  are  cut  into  the  netting 
there  is  danger  that  the  sparks  which  escape  will  set  fire  to  the  combusti- 
ble material  near  the  track.  When  the  engine  “ throws  fire  ” from  this 
cause  the  netting  should  be  renewed.  If  the  engine  “works  water  ” the 
netting  is  liable  to  get  clogged.  It  is  also  liable  to  be  “ gummed  up,” 
especially  if  too  much  oil  is  used  in  lubricating  the  cylinders  and  valves. 
If  the  netting  is  obstructed  the  engine  will  not  make  steam  freely  and  is 
liable  to  “ kick-back,”  that  is,  the  fire  is  liable  to  be  blown  out  of  the 


Care  and  Inspection  of  Locomotives. 


603 


furnace  door  and  burn  the  men  in  the  cab.  Unless  oil  from  the  cylinder 
gets  into  the  netting  the  obstruction  can  usually  be  beaten  out,  but  if  the 
obstruction  is  due  to  an  accumulation  of  gummy  matter,  it  can  often  be 
removed  by  building  a fire  on  top  of  the  netting.  In  this  way  the  oil  in 
the  gummy  matter  is  burned  up,  which  leaves  a dry  material  which  can 
then,  at  least  to  some  extent,  be  beaten  out  of  the  netting. 

Question  786.  What  should  be  noticed  in  connection  with  the  steam 
and  exhaust-pipes  ? 

Answer.  The  steam  pipes  should  be  kept  tight.  If  there  is  any  sus- 
picion that  the  steam  pipes  leak,  the  throttle-valve  should  be  opened 
slightly,  so  as  to  give  the  engine  steam  while  the  smoke-box  door  is  open. 
The  leak  will  then  be  indicated  by  the  escaping  steam.  If  they  leak  the 
joints  must  be  reground.  Exhaust  nozzles  sometimes  get  obstructed  by 
a collection  of  oil  and  dirt,  which  should  be  cleaned  out.  It  should  also 
be  noticed  whether  the  nozzles  are  located  so  that  the  blast  from  the 
exhaust-pipes  is  discharged  in  the  centre  of  the  chimney. 

QUESTION  787.  In  what  way  do  the  grates  get  out  of  order  ? 

Answer.  They  are  liable  to  be  burnt  out,  bent  or  broken.  It  should 
be  observed  whether  the  grate-bars  or  drop-doors  of  the  grate  are  properly 
fastened,  whether  any  of  them  are  broken,  and  whether  the  ashes  have 
been  cleaned  out  of  the  ash-pan,  and  also  whether  the  fire  is  clean — that 
is,  whether  the  grates  are  free  from  cinders  or  clinkers. 

Question  788.  What  should  be  noticed  in  connection  with  the  throttle- 
valve  ? 

Answer.  As  a failure  of  the  throttle-valve  to  work  may  be  the  cause  of 
a most  serious  accident,  it  should  be  certain  that  it  is  in  good  working 
condition,  that  all  the  bolts,  pins,  and  screws,  and  other  accessories  are  in 
good  working  order.  It  should  also  be  known  whether  the  throttle-valve 
is  steam-tight.  This  can  be  learned  by  observing  whether  steam  escapes 
jrom  the  exhaust-pipes  or  cylinder-cocks  when  the  latter  are  open,  the 
reverse-lever  in  full  gear,  and  the  throttle-valve  closed.  If  the  throttle- 
valve  leaks,  enough  steam  may  accumulate  in  the  cylinder,  when  there  is 
no  one  on  the  engine,  to  start  it,  and  in  this  way  cause  a serious  accident. 
The  throttle-lever  should  always  be  fastened  with  a set-screw  or  latch  of 
some  kind  when  the  engine  is  standing  still.  If  a throttle-valve  leaks  it 
should  be  reground.  A disconnected  throttle  is  now  a rare  occurrence, 
but  it  should  be  certain  that  the  connections  are  all  right. 

Question  789,  What  kind  of  attention  must  be  given  to  the  safety- 
valves  ? 


604 


Catechism  of  the  Locomotive. 


Answer.  They  should  be  adjusted  so  as  to  blow  off  at  the  required 
pressure,  and  it  should  be  known  whether  the  springs  retain  their  elasticity, 
as  it  is  affected  by  the  heat  of  the  steam,  which  makes  it  essential  to  renew 
them  occasionally.  One  of  the  safety-valves  should  have  a lever  or  other 
appliance  for  opening  it  in  case  it  is  necessary  to  relieve  the  boiler  of 
pressure,  and  it  should  be  raised  occasionally  to  know  that  it  is  in  good 
working  order. 

Question  790.  What  is  essential  with  reference  to  steam. gauges? 

Answer.  Their  most  important  function  is  to  indicate  the  steam  press- 
ure correctly,  and  as  there  is  no  part  of  a locomotive  more  liable  to  dis- 
order than  the  steam  gauge,  they  should  be  frequently  tested,  and  when- 
ever there  is  any  indication  of  irregularity  in  their  action  it  should  be 
investigated.  When  this  is  done  the  date  should  always  be  marked  on  the 
back  of  the  gauge,  or  some  other  record  of  it  should  be  kept  of  the 
inspection, 

QUESTION  791.  What  kind  of  attention  should  be  given  to  the  other 
boiler  attachments  ? 

Answer.  The  height  of  water  in  the  boiler  should  be  observed  by  test- 
ing it  with  the  gauge-cocks  and  by  noticing  it  in  the  glass  gauge,  if  one 
of  these  is  used.  It  is  also  well  to  blow  out  the  sediment  and  mud  from 
the  glass  gauge  before  starting,  and  to  see  that  the  valves  which  admit 
steam  and  water  to  the  glass  are  open.  They  should,  however,  be  opened 
only  a very  short  distance,  so  that  only  a small  quantity  of  steam  or  hot  water 
will  escape  in  case  the  glass  tube  should  be  broken.  The  whistle-valve 
should  be  kept  tight,  the  gauge-cocks  should  be  kept  clear  by  running  a 
wire  through  them.  A careful  engineer  will  always  know  whether  the 
injectors  work  satisfactorily,  and  if  either  of  them  is  out  of  order  it  should 
be  taken  off  and  a spare  one  substituted  in  its  plaee.  Check-valves  should 
be  taken  down  occasionally  and  cleaned,  and  it  should  be  observed 
whether  the  blower-valves  and  pipes  are  in  good  condition. 

Question  792.  In  inspecting  the  cylinders , pistons  and  guides,  to  what 
points  should  the  attention  be  directed? 

Answer.  It  should  be  known  whether  the  piston  packing  is  properly  set 
out — that  is,  whether  it  is  so  tight  that  it  will  not  “ blow  through ,”  or  leak 
steam  from  one  end  of  the  cylinder  to  the  other,  which,  of  course,  will 
waste  a great  deal  of  steam.  Of  the  two  evils,  it  is,  however,  better  to 
have  piston-packing  too  loose  than  too  tight,  because  if  it  is  too  tight  it 
is  liable  to  cut  or  scratch  the  cylinders  so  as  to  make  it  necessary  to  rebore 
them,  and  at  the  same  time  if  the  packing-rings  are  lined  with  Babbitt 


Care  and  Inspection  of  Locomotives. 


605 


metal,  the  heat  created  by  the  intense  pressure  and  friction  will  melt  the 
metal.  In  some  cases  the  cylinders  become  heated  to  so  high  a tempera- 
ture from  this  'cause  that  the  wood-lagging  with  which  they  are  covered 
on  the  outside  is  burned.  Examination  should  be  made  to  see  that  neither 
the  piston-rods,  pump-plungers  nor  guides  are  bent  or  sprung. 

Question  793.  What  must  be  done  to  keep  the  insides  of  the  cylinders 
in  good  condition — that  is,  to  prevent  the  packing  from  cutting  them? 

Answer.  They  must  be  well  lubricated  when  not  using  steam,  and  the 
packing  must  be  properly  set  up,  not  so  tight  as  to  bind  nor  so  loose  as  to 
blow,  or  allow  the  piston-heads  or  followers  to  rub  on  the  bottoms  of  the 
cylinders,  as  the  two  cast  iron  surfaces  will  then  scratch  each  other.  It  is 
also  important  that  the  piston  be  central  in  the  cylinder;  if  anything, 
have  it  a little  higher  than  central.  It  should  be  set  by  callipering  on  the 
projection  on  the  front  side  which  holds  the  follower-plate  in  place. 

Question  794.  How  can  it  be  known  whether  the  piston-packing  is  too 
loose  or  “ blows  through  ” ? 

Answer.  It  can  usually  be  noticed  in  the  sound  of  the  exhaust,  which 
can  be  heard  very  distinctly  on  the  foot-board  when  the  furnace  door  is 
opened.  If  the  packing  is  not  tight,  it  produces  a peculiar  wheezing  sound 
between  and  after  each  discharge  of  steam.  If  the  packing  leaks,  it  will 
also  be  indicated  by  the  escape  of  steam  from  both  the  cylinders-cocks,  if 
they  are  open,  just  after  the  crank  passes  the  dead  point.  This  will 
usually  show  in  which  of  the  cylinders  the  packing  is  too  loose.  The 
same  thing  will  occur,  however,  if  either  or  both  of  the  main  valves  leak, 
so  that  it  is  often  hard  to  determine  whether  the  “blow”  is  due  to  a leak 
from  the  valve  or  from  the  piston.  Of  course  it  may  sometimes  happen 
that  both  leak,  or  that  the  piston  on  one  side  of  the  engine  and  the  valve 
on  the  other  leak,  so  that  often  the  diagnosis  of  the  disease,  as  the  doctors 
say,  is  extremely  difficult.  Careful  observation  and  experience  will,  how- 
ever aid  a locomotive  runner  in  detecting  such  defects  much  more  than 
any  directions  which  can  be  given  here. 

Question  795.  What  is  meant  by  piston-packing . being  “ follower- 
bound ” ? 

Answer.  It  means  that  when  the  follower-plate  is  bolted  up  hard 
against  the  piston-head  that  it  clamps  or  binds  the  packing-rings  between 
the  plate  and  the  piston-head  so  that  the  rings  cannot  move. 

QUESTION  796.  How  can  it  be  known  whether  the  packing  is  follower- 
bound? 

Answer.  When  the  packing  can  move  as  it  should  between  the  piston- 


606 


Catechism  of  the  Locomotive. 


head  and  follower-plate  its  movement  is  usually  shown  by  marks  on  the 
follower-plate  when  it  is  taken  off.  If  such  marks  are  not  apparent,  and 
there  is  reason  to  think  that  the  packing  is  too  tight,  the  piston  should  be 
taken  out,  the  packing  put  in  place,  and  the  follower-plate  bolted  on. 
The  packing  should  then  be  loose  enough,  so  that  it  can  be  moved  by 
tapping  it  with  a piece  of  wood.  If  it  is  too  tight  a piece  of  paper  should 
be  inserted  between  the  follower-plate  and  piston-head  where  they  are  in 
contact  with  each  other. 

Question  797.  What  is  meant  by  “ setting  out  packing ,”  and  how 
should  it  be  done  ? 

Answer.  “Setting  out  packing”  is  simply  expanding  the  rings  when 
they  get  too  loose.  With  ordinary  spring  packing,  figs.  225  and  226, 
which  is  now  generally  used,  this  is  done  by  screwing  up  the  nuts,  b b b, 
which,  as  was  explained  in  answer  to  Question  338,  compresses  the  springs, 
a a a,  and  thus  expands  the  rings,  A A.  In  doing  this,  as  already  stated, 
great  care  must  be  exercised  not  to  screw  the  nuts  up  too  hard,  and  it  is 
always  better  to  have  the  packing  too  loose  than  too  tight.  Care  must 
also  be  taken  to  keep  the  piston-rods  in  the  centres  of  the  cylinders,  other- 
wise there  will  be  undue  pressure  and  wear  on  the  stuffing-box.  After 
the  nuts  are  screwed  up,  the  position  of  the  piston-head  should  be  tested 
with  a pair  of  calipers.  This  is  done  by  placing  one  leg  of  the  calipers 
against  the  side  of  the  cylinder,  and  setting  them  so  that  the  other  leg 
will  just  touch  the  edge  of  the  projection,  C,  fig.  226,  or  the  end  of  the 
piston-rod.  Then  by  placing  the  calipers  above  and  below,  and  on  each 
side  of  the  piston,  it  will  appear  whether  it  is  too  high  or  too  low  or  too 
near  either  side.  If  the  piston  is  not  in  the  middle  of  the  cylinder,  by 
loosening  the  nuts  on  one  side  and  tightening  them  on  the  other  it  can  be 
moved  to  a central  position.  Ordinarily  this  work  is  intrusted  to  persons 
who  are  employed  for  the  purpose.  A young  locomotive  runner,  fireman, 
or  mechanic  will,  however,  always  do  well  to  familiarize  himself  with  such 
duties,  and,  if  possible,  do  it  himself,  under  the  direction  of  those  who  are 
skilled  in  that  kind  of  work. 

QUESTION  798.  If  the  stuffing-box  of  the  piston-rod  leaks , what  should 
be  done  ? 

Answer.  If  it  is  packed  with  fibrous  packing  and  it  is  in  good  condi- 
tion, it  can  usually  be  made  tight  by  simply  screwing  up  the  nuts  on  the 
gland.  In  doing  this,  they  should  not  be  screwed  up  more  than  is  necessary 
to  make  the  packing  steam-tight.  Any  greater  pressure  only  increases  the 
friction  on  the  piston-rod  unnecessarily.  The  two  bolts  should  be  screwed 


Care  and  Inspection  of  Locomotives. 


607 


up  equally,  otherwise  the  gland  will  be  “ canted — ” that  is,  inclined  so  as 
to  “bind”  or  bear  unequally  and  very  hard  against  the  piston-rod,  and  thus 
be  liable  to  cut  or  scratch  it.  After  packing  has  been  in  the  stuffing-box 
a long  time,  it  becomes  very  hard  and  compact,  and  sometimes  partly 
charred.  It  must  then  either  be  removed  and  new  packing  should  put  be  in, 
or,  if  it  is  in  tolerably  good  condition,  it  can  often  be  made  to  work  well  by 
simply  reversing  it — that  is,  by  putting  that  which  was  at  the  bottom  of  the 
stuffing-box  on  top  and  vice  versa.  Before  packing  is  put  into  a 
stuffing-box,  the  former  should  always  be  thoroughly  oiled. 

QUESTION  799.  What  kind  of  attention  should  be  given  to  piston-rods? 

Answer.  They  should  be  oiled  occasionally  and  kept  keyed  up  tight  in 
the  cross-head  and  piston. 

QUESTION  800.  What  must  be  done  to  keep  the  cross-head  slides  and  the 
guide-bars  in  good  condition? 

Answer.  They  must  be  “ in  line  ” or  parallel  with  the  centre  line  of  the 
cylinder  and  they  must  be  kept  well  lubricated.  There  are  no  parts  of  a 
locomotive  which  require  more  careful  attention  in  order  to  keep  them 
lubricated,  and  thus  prevent  them  from  heating  and  being  “cut,”  than  the 
bearings  on  the  crank-pins  and  the  slides  of  the  cross-head.  A little  lost 
motion  in  the  guides  is  not  a serious  evil  unless  it  becomes  excessive. 

Question  801.  When  the  slides  of  the  cross-heads  are  considerably  worn , 
how  is  the  lost  motion  taken  up  ? 

Answer.  When  there  are  gibs  on  the  cross-head,  the  lost  motion  can 
be  taken  up  by  putting  “ liners ” or  “shims" — that  is,  thin  pieces  of  metal, 
between  them  and  the  cross-head,  so  that  they  will  fill  up  the  space 
between  the  guide-bars.  When  there  are  no  gibs,  the  guide-bars  must  be 
taken  down,  and  the  blocks  between  them  at  each  end  should  be  reduced  in 
thickness  so  as  to  bring  the  bars  nearer  together.  In  doing  this,  great  care 
must  be  taken  that  the  guides  are  accurately  “ in  line  ” with  the  centre 
line  or  axis  of  the  cylinder  when  they  are  put  up  again.  This  work  should 
never  be  intrusted  to  any  excepting  skilled  workmen,  from  whom  those 
who  are  inexperienced  should  seek  instruction. 

Question  802.  What  kind  of  attention  should  be  given  to  the  crank- 
pins  and  connecting-rods  ? 

Answer.  They  are  all  liable  to  break,  and  they  should  be  examined 
often  to  see  whether  there  are  any  cracks  or  flaws  in  them,  or  whether 
any  of  them  are  bent  or  sprung.  Whenever  the  rods  are  taken  down  the 
straps  should  be  looked  over  carefully,  especially  in  the  inside  corners,  to 
see  whether  any  flaws  exist.  Main-rods  are  less  liable  to  break  than  coup- 


608 


Catechism  of  the  Locomotive. 


ling-rods.  Attention  should  be  given  to  the  brass  bearings  of  the  con- 
necting-rods to  see  that  they  are  not  so  loose  as  to  thump,  nor  keyed  so 
tight  on  the  crank  as  to  be  liable  to  heat.  The  latter  can  be  easily  known 
by  moving  the  stub-end  lengthwise  of  the  journal.  They  should  never  be 
so  tight  that  they  cannot  be  thus  moved  with  the  hand.  Especial  atten- 
tion should  be  given  to  seeing  that  all  the  bolts  and  nuts  on  the  connecting- 
rods  are  tight. 

Question  803.  When  the  brass  bearings  of  the  connecting-rods  become 
too  loose  on  their  journals , what  should  be  done  ? 

Answer.  They  must  be  taken  down,  and  the  two  surfaces  in  contact 
must  be  filed  away  so  as  to  bring  them  closer  together.  In  doing  this 
they  must  be  filed  square  with  the  other  surfaces,  otherwise  they  will  not 
bear  equally  on  the  journals  when  they  are  keyed  up.  Before  attaching 
them  permanently  to  the  rods,  they  should  be  keyed  on  the  journal  in  the 
strap  alone,  so  that  it  can  be  known  by  trial  whether  they  move  freely  and 
yet  are  tight  enough  to  prevent  thumping  on  the  journal.  When  they  are 
attached  to  the  rod,  it  is  very  important,  especially  with  coupling  or  par- 
allel-rods, that  the  correct  length  from  centre  to  centre  of  the  bearings  be 
maintained.  It  is  much  better  to  leave  coupling-rods  loose  on  their 
journals,  because,  if  the  bearings  are  keyed  up  tight,  the  rods  are  sure  to 
throw  an  enormous  strain  on  the  crank-pins,  as  the  distance  between  the 
centres  of  the  axles  is  not  always  absolutely  the  same,  owing  to  the  rise 
and  fall  of  the  axle-boxes  in  the  jaws.  It  is  therefore  always  best  to  have 
a little  play  in  the  coupling-rods,  and  it  is  safe  to  say  that  much  more 
mischief  is  done  by  meddling  with  the  coupling-rod  brasses  than  by  neg- 
lecting them. 

Lost  motion  in  a main  connecting-rod  will  cause  a thump,  but  a little 
play  in  coupling-rods  will  do  no  harm.  It  is  better  to  have  the  bearings 
of  coupling-rods  too  loose  than  too  tight.  If  the  coupling-rods  have 
solid  ends  and  bushings  they  require  no  attention  excepting  oiling,  and 
when  the  bushings  are  worn  too  much  they  should  be  taken  out  and 
replaced  with  new  ones. 

Question  804.  How  should  the  valve-gear  be  taken  care  of  ? 

Answer.  The  principal  defects  of  valve  gear  are  due  to  want  of  proper 
lubrication.  The  oil-holes  should  all  be  kept  clear,  otherwise  it  will 
be  impossible  to  keep  the  journals  well  oiled.  The  eccentric  straps  and 
the  link  blocks  are  very  liable  to  be  imperfectly  oiled,  and  when  the  former 
become  dry  and  cut,  they  throw  a great  strain  on  the  eccentric-rods,  which 
is  liable  to  break  them.  When  this  occurs,  the  strap  and  the  portion  of 


Care  and  Inspection  of  Locomotives. 


609 


the  rod  which  is  attached  to  it  revolve  with  the  eccentric,  and  frequently 
a hole  is  thus  knocked  in  the  front  of  the  fire-box,  which  disables  the 
engine.  The  valve  gear  is,  with  the  exception,  perhaps,  of  the  pumps  and 
injector,  the  most  delicate  part  of  the  locomotive,  and  more  liable  to  get 
out  of  order  than  any  other,  and  should  therefore  be  examined  carefully, 
and  if  there  are  any  indications  that  the  eccentric  straps  or  any  of  the 
pins  are  cutting,  they  should  be  taken  apart,  examined,  and  thoroughly 
oiled. 

It  is  usual  now  to  key  eccentrics  fast  to  the  axle  so  that  it  is  impossible 
for  them  to  slip.  If  they  are  fastened  with  set  screws  alone  they  should 
be  examined  occasionally  to  see  whether  they  have  moved  from  their 
original  position. 

All  the  bolts,  nuts,  and  keys  should  be  carefully  examined  to  see  that 
they  are  properly  fastened.  The  bolts  and  nuts  in  the  eccentric  straps  are 
especially  liable  to  become  loose,  and  as  they  are  between  the  wheels,  and 
therefore  not  easy  of  access,  are  often  neglected. 

Question  805.  How  can  it  be  known  whether  the  7nain  valves  of  a 
locomotive  are  tight  ? 

Answer . As  already  indicated,  the  symptoms  which  manifest  them- 
selves when  a valve  leaks  are  very  similar  to  those  which  appear  when 
the  piston  packing  leaks.  If  the  valve  is  moved  to  its  middle  position 
and  steam  is  admitted  into  the  steam-chest,  and  it  then  escapes  from  both 
cylinder-cocks,  it  is  apparent  that  the  valve  is  not  tight.  But  the  valve  faces 
of  locomotives  usually  wear  concave,  because  the  valves  are  worked  most 
about  half-stroke,  so  that  they  will  often  be  tight  when  in  the  centre  of 
the  face,  but  will  leak  at  the  ends  of  the  full  stroke.  This  will  become 
apparent  by  the  peculiar  wheezing  sound,  already  referred  to,  when  the 
engine  is  at  work.  As  has  been  explained,  it  is  often  very  difficult  to 
determine  whether  this  sound  is  due  to  aleak  at  the  pistons  or  the  valves. 
If  the  packing  of  the  valve-stem  leaks,  it  can  be  remedied  in  the  manner 
described  for  making  that  of  the  piston-rod  tight. 

Question  806.  What  is  meant  by  an  engine  “ going  lame  ” ? 

Answer.  It  means  that  one  or  two  of  the  four  blasts  of  steam  from 
the  cylinder  are  not  equal  to  the  others,  so  that  the  exhaust  has  an  irregu- 
lar or  limping  sound. 

Question  807.  To  what  cause  is  “going  lame  ” generally  due? 

Answer.  It  may  be  because  one  or  more  eccentrics  are  not  set  right,  or 
a valve-stem  or  eccentric-rod  is  too  long  or  too  short.  Sometimes  it  is 
due  to  lost  motion  in  the  valve-gear,  or  the  links  may  be  suspended  in 


610 


Catechism  of  the  Locomotive. 


such  a way,  that  when  the  reverse-lever  is  in  a given  position  one  of  them 
hangs  lower  than  the  other.  To  guard  against  the  latter  evil  it  should  be 
observed,  in  setting  the  valves,  whether  they  cut-off  at  the  same  points  of 
the  stroke  on  each  side  of  the  engine. 

Question  808.  How  should  the  running-gear  be  taken  care  of  while 
the  engine  is  in  the  shop  f 

Answer.  First  the  journals  of  the  axles  must  be  kept  well  oiled.  The 
oil-cellars  should  be  taken  down  occasionally  and  cleaned.  They  should 
be  packed  with  woolen  waste,  which  has  more  elasticity  than  cotton  and 
bears  against  the  axle,  while  cotton  waste  packs  down  solid.  With  the 
heavy  loads  now  carried  on  the  driving-axles  of  some  locomotives,  there 
is  often  much  trouble  from  the  journals  heating.  This  is  often  due  to  the 
want  of  end  play  between  the  boxes  and  hubs,  and  collars  on  the  axles. 
This  play  should  be  about  of  an  inch.  The  driving-boxes,  tires,  wheels, 
and  axles  should  be  examined  often  to  discover  flaws,  as  they  are  liable  to 
break.  Engine  axles  usually  break  just  inside  of  the  hub.  When  the 
oil-cellars  are  taken  down,  the  portions  of  the  axles  which  are  inside  of 
the  box  should  be  examined  carefully  for  cracks  or  flaws.  The  axles 
should  be  examined  too  to  see  that  the  wheels  have  not  worked  loose  on 
the  wheel-seat.  When  this  occurs  it  often  becomes  apparent  by  the  oil 
from  the  axle-boxes  working  through  between  the  hubs  of  the  wheel  and 
the  axle.  This  can  be  observed  on  the  outside  of  the  wheels  when  the 
bearings  are  inside,  and  inside  the  wheels  when  the  bearing  is  outside. 

All  the  wheels  of  the  engine  and  tender  should  be  carefully  examined, 
to  see  that  they  are  sound.  A fracture  in  a driving-wheel  is  usually 
apparent  if  the  wheel  is  carefully  examined.  The  condition  of  ordinary 
cast  iron  tender  and  truck-wheels  is  often  revealed  on  striking  them  with  a 
hammer,  when  if  they  are  sound  they  will  give  out  a peculiar  clear  ring; 
whereas  if  they  are  fractured,  the  sound  produced  by  the  blow  of  the  ham- 
mer may  be  dead,  like  that  of  a cracked  bell. 

An  inspector  should  not  rely  entirely  on  this  test,  as  broken  wheels  will 
sometimes  give  a clear  ring.  He  should  examine  them  carefully  for  cracks 
or  other  fractures,  and  should  see  that  the  flanges  are  not  broken,  as  this 
may  occur  and  not  be  revealed  by  the  sound  produced  by  a blow  from  a 
hammer.  If  any  of  the  flanges  of  the  wheels  are  unduly  worn  the  fact 
should  be  reported  to  the  proper  person.  The  wearing  of  flanges  is  due 
to  a variety  of  causes  which  are  sometimes  difficult  to  discover,  such  as 
the  difference  in  the  diameters  of  the  wheels  or  the  hardness  of  the  tires 
in  the  same  axle ; axles  not  parallel  or  the  truck  “ out  of  square,”  centre- 


Care  and  Inspection  of  Locomotives. 


611 


plate  or  pin  not  in  the  centre  of  truck,  bent  axles  or  malformation  of  rails  are 
some  of  the  causes  which  produce  sharp  flanges.  The  steel  tires  of  both 
the  driving  and  the  truck-wheels  should  be  examined  for  flaws  and  broken 
flanges,  and  to  see  whether  they  have  worked  loose  on  the  wheel-centres. 
Moisture  and  dirt  issuing  from  between  the  tire  and  wheel  indicates  that 
the  former  is  becoming  loose,  which  is  more  liable  to  occur  when  the  tires 
are  worn  thin  than  before.  Tires  are  most  liable  to  split  circumferentially, 
or  “ bulge  " sideways.  An  engineer  should  always  be  vigilant  to  detect 
circumferential  flaws  or  any  bulging  which  usually  indicates  the  beginning 
of  a fracture. 

Question  809.  What  are  the  principal  causes  which  make  an  engine 
“pound”  or  “ thump  ” ? 

Answer.  It  is  generally  due  to  lost  motion  somewhere.  If  an  engineer 
hears  a “knock,”  he  should  examine  to  see  whether  there  is  lost  motion  in 
either  of  the  ends  of  the  main  connecting-rods.  Lost  motion  in  coup- 
ling-rods is  not  liable  to  cause  a thump,  although  they  may  be  so  loose 
that  their  side  motion  may  make  them  rattle.  A loose  piston-rod  in  the 
cross-head  or  piston  may  cause  a “ pound.”  The  most  difficult  cause  to 
discover  is  when  the  piston-rod  gets  loose  in  the  piston,  because  it  cannot 
be  examined  when  the  engine  is  working.  If  a piston  strikes  the  cylinder- 
head  it  will  also  cause  a “ knock.” 

The  working  of  the  driving-boxes  up  and  down  between  the  jaws  will  in 
time  wear  them  so  that  there  will  be  some  lost  motion.  This  or  a loose 
journal  bearing  in  one  of  the  driving-boxes  will  be  indicated  by  a thump 
when  the  cranks  pass  the  dead-point.  A similar  thump  will,  however,  be 
produced  by  lost  motion  in  the  boxes  of  the  main  connecting-rod,  so  that 
it  is  difficult  to  determine,  without  special  examination,  the  cause  which 
produces  the  concussion.  By  reversing  the  engine  with  a little  steam  on 
when  it  is  standing  still,  it  can  be  known  whether  there  is  lost  motion  in 
the  driving-boxes,  and  by  watching  them  carefully  it  can  be  seen  whether 
they  are  loose  between  the  wedges  or  on  the  journal  of  the  axle. 

It  is  therefore  best  when  an  engine  works  with  a thump  at  each  revolu- 
tion for  the  runner  to  stand  by  the  side  of  it  where  he  can  touch  the  con- 
necting-rods and  driving-wheels,  and  then  have  the  fireman  open  the 
throttle-valve,  so  as  to  move  the  engine  slowly.  If  the  lost  motion  is  in 
the  connecting-rods  it  can  be  felt  by  the  jar  as  it  passes  the  dead-points. 
The  same  is  true  of  lost  motion  in  the  jaws,  which  can  be  felt  by  touch- 
ing the  driving-wheels.  When  the  jaws  become  worn  the  lost  motion  can 
be  taken  up  by  moving  up  one  or  both  of  the  wedges.  When  this  is  done. 


612 


Catechism  of  the  Locomotive. 


great  care  must  be  taken  to  keep  the  centres  of  the  driving-axles  the 
same  distance  apart  on  both  sides  of  the  engine,  and  also  to  keep  their 
centre  lines  square  with  the  frames.  In  the  best  designed  locomotives 
the  driving-boxes  now  have  only  one  wedge,  which  is  usually  on  the  back 
side  of  the  box,  as  shown  in  fig.  349.  The  frame  in  front  of  the  box  is 
protected  by  a straight  shoe  or  by  a wedge  the  full  length  of  the  jaw  so 
that  it  cannot  be  moved  up  or  down.  This  is  done  so  that  the  position  of 
the  box  cannot  be  changed  by  carelessly  or  ignorantly  moving  one  wedge 
up  and  the  other  down.  There  should  always  be  centre-punch  marks 
placed  on  the  frames  or  guide-yokes  on  each  side  of  the  engine  in  front  of 
the  main  axle,  and  at  equal  distances  from  its  centres,  so  that  when  the 
boxes  or  jaws  become  worn  the  position  of  the  axle  can  be  adjusted  with 
a tram  from  these  marks.  Of  course,  if  the  main  axle  is  square,  it  is  easy 
to  adjust  the  trailing  axle  from  it  with  a tram.  If  the  axles  are  not  square 
with  the  frames  and  parallel  with  each  other,  the  engine  will  run  toward 
one  side  or  the  other  of  the  track,  according  to  the  inclination  of  the  axles. 
It  sometimes  happens  that  the  bolts  which  hold  up  the  wedges  in  the  jaws 
are  broken.  When  this  occurs  the  wedge  drops  down,  and  of  course  the 
box  has  so  much  lost  motion  that  it  soon  manifests  itself  in  the  working 
of  the  engine.  These  bolts,  and  also  those  which  hold  up  the  clamps  on 
the  frames  at  the  bottom  of  the  jaws,  should  be  examined  when  the  engine 
is  inspected,  so  as  to  be  sure  they  are  in  good  condition. 

Question  810.  What  precaution  must  be  taken  with  reference  to 
springs , hangers , and  equalizers  ? 

Answer . Like  all  other  parts,  they  should  be  examined  often  to  see 
that  they  are  in  good  condition,  and  it  should  be  observed  whether  the 
springs  come  in  contact  with  the  boiler — if  they  do  they  may  rub  against 
it  and  wear  a hole  in  it. 

Question  811.  In  the  examination , care  of,  and  repairs  to  injectors, 
what  precaution  should  be  observed ? 

Answer . 1.  The  pipe  connections  should  be  kept  perfectly  tight  to 
prevent  air  leaks. 

2.  The  steam-valves  should  be  kept  tight  to  prevent  escaping  steam 
from  heating  the  suction-pipe,  which  interferes  with  the  formation  of  a 
vacuum  and  prevents  the  instrument  from  lifting  the  water. 

3.  The  packing  of  the  different  spindles  and  valve-stems  should  be 
kept  in  good  condition,  so  that  they  will  be  steam  or  air-tight. 

4.  The  nozzles  of  the  injector  must  be  taken  out  and  thoroughly 
cleaned  more  or  less  often — according  to  the  character  of  the  water  used 


Care  and  Inspection  of  Locomotives. 


613 


. — so  as  to  keep  them  as  far  as  possible  free  from  incrustation.  Mineral 
oil  drawn  with  the  water,  when  the  injector  is  at  work,  will  have  an 
excellent  effect  in  keeping  it  free  from  scale.  Some  injectors  are  arranged 
to  receive  an  oil-cup  for  this  purpose. 

5.  The  boiler  check-valves  must  be  kept  tight  and  free  from  dirt  and 
incrustation,  to  prevent  the  back-flow  of  hot  water  and  the  sticking  of  the 
valves. 

QUESTION  812.  If  a lifting  injector  is  tested  and  does  not  lift  the  water 
properly , to  what  causes  may  it  be  due? 

Answer . It  may  be  due  : 

1.  To  a leak  in  the  steam-valve,  and  the  consequent  heating  of  the 
suction-pipe  to  such  a degree  as  to  prevent  the  formation  of  sufficient 
vacuum  in  that  pipe.  This  defect  can  be  remedied  only  by  grinding  the 
steam-valves,  so  as  to  make  them  tight.  Such  a leak  will  be  indicated  by 
an  escape  of  steam  from  the  overflow  when  the  steam-valves  are  closed. 

2.  To  a leak  in  the  suction-pipe  or  its  connection,  in  which  case  the 
air  drawn  in  by  applying  the  lifting  jet  will  prevent  the  formation  of  the 
vacuum.  Such  a leak  can  be  detected  by  closing  the  heater-cock  and 
opening  the  main  steam-valve  only — if  there  is  a separate  lifting  jet — or, 
with  a single  lever  instrument,  by  opening  both  steam-valves  at  once.  The 
steam  blowing  back  to  the  tank  will  then  escape  through  the  leak,  if  there 
is  one.  The  trouble  will  usually  be  remedied  by  tightening  up  the  suction- 
pipe  connections. 

3.  To  a leak  in  the  boiler  check-valves  and  the  consequent  heating  of 
the  suction-pipe  by  the  hot  water  from  the  boiler  flowing  back  through 
the  injector.  Grinding  the  check-valve  will  remedy  this. 

QUESTION  813.  If  the  injector  lifts  the  water,  but  does  not  take  it  up 
and  throw  it  out  through  the  overflow,  or  the  stream  flowing  into  the  boiler 
breaks,  to  what  causes  ?nay  it  be  due  ? 

Answer.  1.  To  a slight  leak  in  the  suction-pipe,  not  sufficient  to  pre- 
vent a short  lift,  but  enough  so  that  the  air  drawn  in  disturbs  the  current 
in  the  nozzles.  Such  a leak  can  be  detected  and  remedied  as  explained  in 
answer  to  the  previous  question. 

2.  To  obstructions  in  the  suction-pipe,  floating  matter,  bits  of  wood, 
hemp,  leaves,  obstructions  in  the  strainer,  or  not  sufficiently  large  strainer 
to  admit  the  proper  supply  of  water.  If  the  strainer  is  obstructed  it  must 
be  taken  out  and  cleaned.  The  present  strainers  in  general  use,  consist- 
ing of  a perforated  cone  inside  of  the  suction-pipe,  are  a frequent  cause  of 
trouble  in  the  working  of  injectors.  They  are  usually  not  large  enough, 


614 


Catechism  of  the  Locomotive. 


and  difficult  of  access  for  cleaning.  The  suction-pipe  itself  can  be  cleaned 
by  blowing  steam  through  it  with  the  heater-cock  closed. 

3.  To  boiler  check-valves  sticking  fast,  on  account  of  corrosive  incrus- 
tation, or  dirt  in  the  valve-chamber,  which  prevents  the  free  action  of  the 
valves.  The  remedy  is  to  open  the  valve-chamber,  and  thoroughly  clean 
the  valve,  its  seat,  and  guides. 

4.  To  leaky  heater-cock  check,  which  will  be  indicated  by  a sputtering 
sound,  which  is  again  caused  by  the  air  taken  in  through  the  overflow. 
Grinding  the  check  will  remedy  it. 

Question  814.  What  must  be  done  to  keep  oil-cups  in  good  condition? 

Answer.  The  principal  thing  to  do  is  to  keep  them  clean,  free  from 
dirt  and  gum,  and  adjust  the  spindles — if  they  have  any — so  that  the  oil 
will  flow  freely,  and  yet  not  too  rapidly,  on  the  surfaces  exposed  to 
friction. 

In  inspecting  a locomotive,  it  should  be  observed  whether  the  oil-cups 
are  screwed  down  tight  to  the  part  to  which  they  are  attached.  They  are 
liable  to  work  loose  and  be  lost,  or  by  getting  between  some  of  the  work- 
ing parts,  to  cause  a breakdown. 

Question  815.  What  else  should  a locomotive  runner  observe  in  making 
an  inspection  of  his  locomotive  ? 

Answer.  A good  locomotive  runner  will  always  give  ample  time  for 
the  inspection  of  his  engine  before  starting  out.  It  is  assumed  that  the 
inspection  which  has  been  described  has  been  made  after  the  engine  has 
completed  a trip,  and  when  there  is  no  fire  in  the  fire-box.  Before  start- 
ing, a careful  locomotive  runner  should  begin  at  the  front  of  his  engine 
and  see  that  the  pilot  and  all  its  fastenings  are  in  good  condition.  He 
should  be  especially  alert  in  inspecting  this,  as  well  as  all  other  parts  of 
the  locomotive,  to  see  that  none  of  the  bolts  and  nuts  have  been  lost,  and 
that  they  are  screwed  up  tight,  and  the  keys  are  all  right. 

The  engine  and  tender  should  occasionally  be  lifted  up  from  the  centre 
plates  of  the  trucks,  and  the  plates  should  be  lubricated  with  tallow.  It 
often  happens  that  these  become  dry,  so  that  they  are  difficult  to  turn 
when  the  weight  rests  on  them,  and  therefore  they  will  not  adjust  them- 
selves easily  to  the  curves  of  the  track. 

It  should  be  certain  that  the  brakes  on  the  tender  are  in  good  working 
condition — that  is,  that  the  bolts,  nuts,  and  keys  are  all  secure,  the  levers, 
rods,  and  chains  properly  connected,  and  the  shoes  fastened  and  not  too 
much  worn.  If  either  an  atmospheric  or  vacuum  brake  is  used,  it  should 
be  tested  before  starting,  as  was  fully  explained  in  Chapter  XXVII. 


Care  and  Inspection  of  Locomotives. 


615 


The  inside  of  the  water-tank  should  also  be  examined  occasionally,  to 
see  whether  it  is  clean,  and  if  not  it  should  be  thoroughly  washed  out.  If 
the  tank  is  new  or  has  had  any  repairs  done  to  it,  the  inside  should  be 
carefully  examined  to  see  whether  any  waste  rags  or  other  objects  have 
been  left  in  it,  as  these  might  obstruct  the  strainers  over  the  water-supply 
pipes.  The  strainers  should  be  examined  occasionally  to  see  whether 
they  are  clear.  The  man-hole  of  the  tank  should  always  be  covered,  ex- 
cepting while  taking  water,  so  as  to  exclude  cinders  and  coal,  which  are 
liable  to  obstruct  the  pump  valves.  It  is  hardly  necessary  to  say  that  it 
must  always  be  certain  before  starting  that  there  is  enough  water  in  the 
tank  to  feed  the  boiler  until  the  next  point  is  reached  at  which  a supply 
can  be  obtained.  The  sand-box  must  also  be  filled,  the  bell-rope  be  in  good 
condition,  and  if  running  at  night  the  reflector  of  the  head-light  must  be 
polished  and  the  lamp  supplied  with  oil  and  the  wick  trimmed  so  as  to 
burn  brilliantly.  The  locomotive  runner  must  also  see  that  the  proper 
signals  are  displayed  in  front  of  his  engine. 

Question  816.  What  precaution  should  be  taken  if  any  repairs  have 
been  done  to  the  engine  ? 

Answer.  The  parts  which  have  been  repaired  should  be  examined  care- 
fully to  see  that  they  have  been  properly  done,  and  if  they  require  lubrica- 
tion, it  should  receive  especial  attention,  as  new  parts  are  always  liable  to 
heat  or  cut. 

Question  817.  What  tools , etc.,  should  every  locomotive  runner  on  the 
road  carry  ? 

Answer.  A coal  shovel,  coal  pick,  long-handled  hoe*  and  poker,  a pair 
of  jacks — either  screw  or  hydraulic,  chains,  rope  and  twine  to  be  used  in 
case  of  accident,  a heavy  pinch-bar  for  moving  the  engine,  a small  crow- 
bar, oil-cans  with  short  and  long  spouts  and  another  smaller  one  with 
spring  bottom,  a steel  and  a copper  hammer,  a cold  and  a cape  chisel,  a 
hand-saw,  axe  and  hatchet,  one  large  ami  one  small  monkey-wrench  and 
a full  assortment  of  solid  wrenches  for  the  bolts  and  nuts  of  the  engine, 
cast-iron  plugs  for  plugging  tubes,  with  a bar  for  inserting  them,  two  sheet- 
iron  pails  or  buckets,  different  colored  lanterns  and  flags,  according  to  the 
colors  used  for  signals  on  the  line,  and  a box  with  a half  dozen  torpedoes. 

Question  818.  What  duplicate  parts  should  be  carried  with  the  engine  ? 

Answer.  Keys,  bolts,  and  nuts  for  connecting-rods,  split-keys,  wedge- 
bolts,  bolts  for  oil-cellars  of  driving  and  truck-boxes,  driving  and  truck 
spring-hangers,  wooden  blocks  for  fastening  guides  in  case  of  accident. 


* These  are  of  course  not  needed  on  wood-burning  engines. 


616 


Catechism  of  the  Locomotive. 


blocks  for  driving-boxes  and  links,  a half  dozen  f-inch  bolts,  from  6 inches 
to  2 feet  long,  to  be  used  in  case  of  accident,  two  extra  water-gauge 
glasses,  two  glass  head-light  chimneys. 

Question  819.  What  should  be  observed  in  lubricating  a locomotive  or 
any  other  machinery? 

Answer.  The  most  important  thing  to  observe  is  that  the  oil  reaches 
the  surface  to  be  lubricated.  It  is  of  much  greater  importance  that  the 
lubricant  should  reach  the  right  place  than  that  a large  quantity  should 
be  used.  A few  drops  carefully  introduced  on  a journal  will  do  much 
more  good  than  a large  quantity  poured  on  the  part  carelessly.  For  this 
reason  all  oil-cups  and  oil-holes  should  be  kept  clean  so  as  to  form  a free 
passage  for  the  oil.  It  should  also  be  remembered  that  no  automatic  oil- 
cup  will  work  satisfactorily  a great  while  unless  it  receives  the  attention 
which  all  of  them  require. 


CHAPTER  XXXIV. 


RUNNING  LOCOMOTIVES. 

Question  820.  Before  starting  the  fire  in  a locomotive  what  should  be 
observed ? 

Answer.  It  should  always  be  noticed  before  kindling  the  fire  whether 
the  boiler  has  the  requisite  quantity  of  water  in  it ; that  all  cinders,  clink- 
ers, and  ashes  are  removed  from  the  grates  and  ash-pan,  and  from  the 
brick-arch  or  water-table,  if  the  boiler  has  either  of  these  appliances ; that 
the  grates  and  drop-door  are  in  their  proper  position  and  securely  fastened  ; 
that  the  throttle-valve  is  closed  and  the  lever  secured ; and,  if  the  boiler 
was  filled  through  the  feed-pipe  by  means  of  the  engine-house  hose,  it 
should  be  observed  whether  the  check- valves  are  closed.  If  they  are  not 
closed  it  will  be  shown  by  the  escape  of  water  when  the  engine-house  hose 
is  detached,  or  by  the  water  and  steam  blowing  back  into  the  tank  when 
the  tender-hose  are  coupled  up,  and  after  steam  is  generated  in  the  boiler. 
Locomotive  boilers  are  sometimes  seriously  injured  by  building  a fire  in 
them  when  they  have  not  been  filled  with  water.  This  can  only  occur 
from  the  grossest  carelessness  on  the  part  of  the  person  who  starts  the 
fire,  and  is  or  should  be  a cause  for  suspension  or  discharge  of  the  person 
who  is  guilty  of  such  neglect.  In  filling  a boiler  it  must  be  remembered, 
however,  that  when  the  water  is  heated  it  will  expand,  and  that  when 
bubbles  of  steam  are  formed  they  will  mix  with  the  water  and  thus 
increase  its  volume,  so  that  after  the  water  is  heated  its  surface,  as 
shown  by  the  water-gauge  and  gauge-cocks,  will  be  considerably  higher 
than  when  it  is  cold. 

Question  821.  How  should  the  fire  in  a locomotive  be  started  ? 

Answer.  It  should  be  started  slowly,  so  as  not  to  heat  any  one  part 
suddenly.  Probably  the  greatest  strains  which  a locomotive  boiler  has 
to  bear  are  those  due  to  the  unequal  expansion  and  contraction  of  its  dif- 
ferent parts.  When  the  fire  is  started,  of  course  the  parts  exposed  to  it 
are  heated  first,  and  consequently  expand  before  the  others  do.  If  the 
fire  is  kindled  rapidly,  the  heating  surfaces  will  become  veiy  hot  before 
the  heat  is  communicated  to  the  parts  not  exposed  to  the  fire.  Thus,  the 


618 


Catechism  of  the  Locomotive. 


tubes,  for  example,  will  be  expanded  so  as  to  be  somewhat  longer  than  the 
outside  shell  of  the  boiler,  and  therefore  there  will  be  a severe  strain  on 
the  tube-plates,  which  will  be  communicated  to  the  fire-box,  stay-bolts, 
braces,  etc.  The  inside  plates  of  the  fire-box  will  also  become  much  hotter 
than  those  on  the  outside,  and  as  they  are  rigidly  fastened  to  the  bar  to 
which  both  the  inside  and  the  outside  shells  are  attached  at  the  bottom, 
the  expansion  of  the  inside  plates  will  all  be  upward,  which  thus  strains 
the  stay-bolts  in  that  direction.  As  the  motion  due  to  this  expansion  is 
greatest  near  the  top  of  the  fire-box,  the  top  stay-bolts  are  of  course 
strained  the  most,  and  it  is  those  in  that  position,  as  has  already  been 
pointed  out,  which  are  the  most  liable  to  break.  When  steel  plates  are 
used,  the  expansion  or  contraction  sometimes  cracks  them,  and  occa- 
sionally hours  after  the  fire  is  withdrawn  from  the  fire-box,  the  inside 
plates  will  crack  with  a report  like  that  of  a pistol.  It  is,  therefore,  very 
important  both  to  heat  and  cool  a locomotive  boiler  slowly,  and  it  is  best 
to  kindle  the  fire  several  hours  before  the  engine  starts  on  its  run. 

Question  822.  If  the  fire  in  the  fire-box  has  been  banked , what  should 
be  done  before  leaving  the  engine-house  ? 

Answer.  The  fire  should  be  broken  up  with  a bar  and  the  ashes  shaken 
out  of  it,  and  fresh  coal  should  be  thrown  on  the  fire  if  it  is  needed. 

Question  823.  What  should  be  done  whe7i  the  locomotive  leaves  the 
engine-house  and  before  the  train  is  started? 

Answer.  Before  leaving  the  engine-house  the  cylinder-cocks  should  be 
open,  so  that  any  water  or  steam  which  is  condensed  in  warming  the  cyl- 
inders can  escape.  The  engineer  should  know  that  the  tank  is  filled  with 
water,  the  sand-box  with  sand,  and  that  there  is  a proper  supply  of  oil, 
waste,  packing,  tools,  and  lamps  on  the  engine.  Before  the  engine  is 
started  from  the  engine-house  the  bell  should  be  rung  and  time  enough 
allowed  for  any  w'orkmen  employed  about  the  engine  to  get  out  of  the 
way.  This  rule  must  be  scrupulously  obeyed  under  all  circumstances , and 
a locomotive  should  never  be  started  without  first  giving  such  a signal. 
Without  it  there  is  always  danger  that  some  one  about  the  engine  will  be 
hurt  or  killed.  While  running  from  the  engine-house  to  the  train  the 
engineer  should  observe  very  carefully  the  working  of  all  the  parts  of  his 
engine,  and  as  far  as  possible  see  that  they  are  in  good  working  condi- 
tion. If  the  engine  is  without  a steam  or  air-brake,  the  fireman  should 
operate  the  hand-brake  on  the  tender  when  it  is  needed.  The  junction 
with  the  train,  especially  when  it  is  a passenger  train,  should  be  made 
very  gently,  as  otherwise  passengers  may  be  injured  by  the  shock.  Before 


Running  Locomotives. 


619 


starting,  the  engineer  should  see  himself  that  the  engine  and  tender  are 
securely  coupled  together,  that  the  frictional  parts  are  properly  lubricated, 
as  explained  heretofore,  that  the  fire  is  in  good  condition,  and  that  the 
requisite  quantity  of  steam  has  been  generated.  If  the  steam  is  too  low, 
the  blovrer  should  be  started,  which  stimulates  the  fire.  He  should  also 
test  the  air-brakes,  as  explained  in  another  chapter. 

Question  824.  When  the  train  is  ready , how  should  the  engine  be 
started ? 

Answer.  After  the  signal  to  start  is  given  by  the  conductor,  the 
engineer  also  gives  a signal  by  either  ringing  the  bell  or  blowing  the 
whjstle.  The  latter  should,  however,  be  used,  especially  at  stations,  as 
little  as  possible,  on  account  of  the  risk  of  frightening  horses  and  the 
shock  which  it  produces  on  persons  who  are  unaccustomed  to  hearing  it, 
or  are  suffering  from  any  nervous  disorder.  After  giving  the  requisite 
signal,  the  engineer  places  the  reverse  lever  so  that  the  valve  will  work 
either  in  full  gear  or  very  near  it.  He  then  opens  the  throttle  slowly  and 
cautiously  so  as  to  start  the  train  gradually.  If  the  train  is  a very  heavy 
one,  it  is  best  to  back  the  engine  so  as  just  to  “take  up  the  slack  of  the 
train  ” — that  is,  to  push  the  cars  together  so  that  there  will  be  no  space 
between  them,  and  thus  compress  the  car  draw-springs.  When  the  cars 
stand  in  this  way,  those  at  the  front  end  of  the  train  are  started  one  after 
another,  which  makes  the  start  easier  than  it  would  be  if  it  were  necessary 
to  start  them  all  at  once.  If  the  throttle  is  opened  too  rapidly,  the  driv- 
ing-wheels are  apt  to  slip,  but  with  a heavy  train,  even  with  the  greatest 
care,  this  is  liable  to  occur.  If  the  train  cannot  be  started  otherwise,  the 
rails  must  be  sanded  by  opening  the  valves  in  the  sand-box.  As  little 
sand  should  be  used  as  possible,  because  the  resistance  of  cars  running  on 
sanded  rails  is  somewhat  greater  than  on  clean  rails,  and  thus  the  train 
is  more  difficult  to  draw  after  it  reaches  the  rails  to  which  sand  has  been 
applied.  The  difficulty  to  be  overcome  may  thus  be  increased  by  the 
means  employed  to  overcome  it. 

While  the  train  is  slowly  set  in  motion  the  fireman  and  engineer  should 
ascertain  by  watching  whether  the  whole  train  moves  together,  and  that 
none  of  the  couplings  are  broken  in  starting,  and  also  whether  any  signal 
is  given  to  stop,  as  is  sometimes  necessary  after  the  train  has  started.  On 
leaving  the  station  he  should  observe  whether  all  the  signals  indicate  that 
the  track  is  clear  and  that  the  switches  are  set  right,  and  also  look  out  for 
obstructions  on  the  track.  The  train  should  always  be  run  slowly  and 
cautiously  until  it  has  passed  all  the  frogs,  switches,  and  crossings  of  the 


620 


Catechism  of  the  Locomotive. 


station  yard,  and  not  until  then,  and  when  the  engineer  has  seen  that 
everything  is  in  order,  should  he  run  at  full  speed.  As  the  engine  gains 
in  speed  the  reverse  lever  should  be  thrown  back  and  nearer  the  centre  of 
the  quadrant  or  sector,  so  as  to  cut  off  “ shorter.” 

Question  825.  After  the  engine  is  started,  how  can  it  be  run  most 
economically  ? 

Answer.  The  advantage  of  using  steam  expansively  has  already  been 
explained  in  Chapter  VII ; it  is  more  economical  to  use  steam  of  a high 
pressure,  which  is  done  by  keeping  the  throttle-valve  wide  open,  and  then 
regulating  the  speed  by  cutting  off  shorter — that  is,  expanding  it  more — 
than  it  is  to  throttle  the  steam.  If  the  speed  is  reduced  by  partly  closing 
the  throttle-valve,  the  steam  is  wire-drawn,  and  it  then  produces  less  use- 
ful effect  than  it  would  if  it  was  admitted  into  the  cylinder  at  full  boiler 
pressure. 

There  is  also  another  practical  difficulty  in  using  steam  of  a high  press- 
ure and  running  with  the  throttle  wide  open  and  regulating  the  speed 
with  the  reverse  lever  alone.  The  link-motion,  as  has  already  been  ex- 
plained, will  not  be  effective  in  cutting  off  at  a point  below  about  one- 
quarter  of  the  stroke.  Now  it  often  happens,  even  when  cutting  off  at 
that  short  point,  with  light  trains  on  a level  or  slightly  descending  grade, 
that  the  speed  will  be  too  great  if  the  throttle  is  wide  open  and  with  full 
steam  pressure  in  the  boiler.  When  this  is  the  case,  it  is  absolutely 
necessary  to  reduce  the  speed  by  partly  closing  the  throttle.  Undoubtedly 
if  valve  gear  for  locomotives  was  so  constructed  that  steam  could  be  cut 
off  effectively  at  a shorter  point  of  the  stroke,  it  would  result  in  some  in- 
creased economy  in  the  use  of  steam. 

The  engineer  should  aim  to  run  at  as  nearly  uniform  speed  as  possible, 
and  in  order  to  do  so  should  divide  the  distance  between  stopping  points 
and  the  time  given  for  running  it  into  as  small  divisions  as  he  conveniently 
can,  so  as  to  be  able  to  tell  as  often  as  possible  whether  he  is  running  too 
fast  or  too  slow,  and  thus  travel  over  the  shorter  spaces  in  corresponding 
periods  of  time. 

Question  826.  How  should  the  boiler  be  fed? 

Answer.  The  feeding  of  the  boiler  should,  if  possible,  be  continuous, 
and  the  quantity  of  water  pumped  into  should  be  adjusted  to  the  amount 
of  work  which  the  engine  is  doing.  Ordinarily  one  pump  or  injector  is 
more  than  sufficient  for  feeding  the  boiler,  so  that  usually  only  the  one  on 
the  right  side  of  the  engine,  where  the  engineer  stands,  is  used.  The  flow 
of  the  water  with  a pump  is  regulated  by  partly  opening  or  closing  the 


Running  Locomotives. 


621 


feed-cock.  In  feeding  the  boiler  it  must  be  seen  that  the  water  is  neither 
too  high  nor  too  low.  If  it  is  too  low  there  will  be  danger  of  overheating 
the  crown-plates  or  even  of  an  explosion  ; if  it  is  too  high,  the  steam  space 
in  the  boiler  is  diminished  unnecessarily,  and  will  cause  the  water  to  rise 
in  the  form  of  a spray,  and  thus  be  carried  into  the  cylinders  with  the 
steam,  or  the  boiler  will  primeox  foam , as  it  is  called.  This  water,  if  it 
collects  in  the  cylinder,  as  already  explained,  may  by  the  concussion  pro- 
duced by  the  motion  of  the  piston  break  the  cylinder. 

Question  827.  What  is  the  cause  of  priming  in  a boiler? 

Answer.  One  of  the  chief  causes  of  priming  is  impure  water.  If  grease, 
oil,  or  soap  gets  into  the  boiler,  it  is  almost  sure  to  cause  priming.  Mud 
or  other  dirt  is  also  liable  to  cause  it.  It  is  often  due  to  the  difference  in 
the  temperature  and  pressure  in  the  water  below  and  the  steam  above. 
Thus,  if  we  have  a boiler  in  which  the  water  is  heated  to  a temperature 
due  to  150  lbs.  effective  pressure,  or  366°,  and  we  then  open  the  throttle- 
valve  suddenly,  so  as  to  relieve  the  pressure  on  top  of  the  water,  there  will 
at  once  be  a rapid  generation  of  steam  in  the  water  which  will  rush  to  fill 
the  space  from  which  the  steam  has  been  drawn,  just  as  the  gas  in  soda 
water  will  rush  toward  the  mouth  of  a bottle  when  the  cork  is  drawn. 
This  newly  generated  steam  will  be  formed  at  the  hottest  part  of  the 
boiler  first — that  is,  next  to  the  heating  surface.  It  will,  therefore,  happen 
that  as  soon  as  the  pressure  is  relieved,  bubbles  of  steam  from  all  parts 
of  the  heating  surface  of  the  boiler  will  flow  to  the  point  at  which  the 
steam  escapes.  The  motion  of  these  bubbles  will  be  so  rapid  that  large 
quantities  of  water  will  be  carried  with  them.  The  same  thing  will  also 
occur  if  the  heat  of  the  water  is  increased  very  rapidly.  The  water  will 
then  become  hotter  than  the  temperature,  due  to  the  pressure  of  the  steam 
above  it,  and  consequently  there  will  be  a rapid  formation  and  escape  of 
bubbles  of  steam  from  the  water,  which  will  thus  have  the  same  effect 
as  they  would  have  if  the  steam  pressure  was  reduced. 

The  amount  of  water  carried  up  with  the  steam  is  increased  if  the 
escape  of  the  latter  is  obstructed  in  any  way,  owing  to  imperfect  circula- 
tion of  water  in  the  boiler,  or  by  floating  impurities,  such  as  oil,  on  the 
surface.  When  this  condition  of  things  exists,  the  ebullition  is,  as  it  were, 
convulsive,  and  the  water  is  thus  carried  up  with  the  steam  when  it 
escapes.  Priming  is  also  probably  due  in  some  measure  to  the  flow  of 
steam  over  the  surface  of  the  water  to  the  point  of  outflow,*  carrying 
particles  of  water  with  it  just  as  a high  wind  will,  when  blowing  over  the 
crests  of  the  waves  of  the  sea. 


* Wilson  on  Steam  Boilers. 


622 


Catechism  of  the  Locomotive. 


When  steam  is  drawn,  as  it  usually  is  in  locomotives,  from  the  top  of 
the  dome  to  which  the  safety-valves  are  attached,  the  tendency  to  prime 
is  very  much  increased  when  they  are  blowing  off,  so  that  some  engineers 
advocate  the  use  of  two  domes,  from  both  of  which  the  supply  of  steam 
is  sometimes  drawn,  and  in  other  cases  the  safety-valves  are  mounted  on 
one,  and  the  steam-pipe  is  placed  in  another  dome.  Whenever  the  safety- 
valves  begin  blowing  off  steam,  the  pressure  in  the  boiler  should  be 
reduced  as  soon  as  possible,  not  only  because  when  they  are  blowing  off 
it  tends  to  produce  priming,  but  because  the  steam  which  escapes  from 
them  is  wasted,  The  pressure  can  be  most  economically  reduced  either 
by  increasing  the  amount  of  water  which  is  fed  into  the  boiler,  or  by  open- 
ing the  heater  cocks  and  allowing  the  steam  to  escape  into  the  tank  and 
thus  warm  the  water  in  the  tank.  If  the  boiler  is  too  full,  the  former 
method  cannot  be  employed,  and  in  heating  the  water  in  the  tank  the 
engineer  must  be  careful  not  to  get  it  too  hot,  because  in  that  case  neither 
the  pumps  nor  the  injectors  will  work  satisfactorily,  and  the  paint  on  the 
tenders  is  also  liable  to  be  blistered  and  destroyed  by  the  heat.  By  feel- 
ing the  tank  with  the  hand  it  can  soon  be  discovered  whether  the  water 
is  too  hot.  If  the  steam  pressure  cannot  be  reduced  in  any  other  way,  the 
furnace  door  must  be  partly  opened. 

The  use  of  muddy  water  will  also  sometimes  cause  a boiler  to  prime.  It 
is  probable  that  priming  is  sometimes  due  to  the  formation  of  foam  on 
the  surface  of  the  water,  and  therefore  all  priming  is  often  called  foaming; 
whereas  it  is  thought  that  often  a boiler  will  prime  when  the  water  does 
not  foam.  More  accurate  information  regarding  the  priming  of  boilers  is, 
however,  much  needed,  as  many  of  the  phenomena  have  thus  far  not  been 
satisfactorily  explained.  The  principal  causes  of  priming  in  ordinary 
practice  are,  however,  undoubtedly  owing  to  defective  circulation,  too 
little  steam  room,  impure  water,  or  too  much  water  in  the  boiler. 

Question  828.  How  can  it  be  known  whether  an  engine  is  priming , 
and  what  should  be  done  to  prevent  it  ? 

Answer.  The  priming  of  a boiler  can  be  known  by  the  white  appear- 
ance of  the  steam  which  escapes  from  the  chimney  and  the  cylinder  cocks. 
Dry  steam  always  has  a bluish  color.  When  an  engine  primes  or  works 
water  into  the  cylinders,  it  is  usually  indicated  by  a peculiar  muffled  or 
dead  sound  of  the  exhaust,  which  from  this  cause  loses  its  distinctly 
defined  and  sharp  sound.  This  can  be  observed  best  when  the  furnace 
door  is  opened.  It  is  also  indicated  by  the  discharge  from  the  gauge-cocks 
as  the  steam  from  the  upper  cocks  is  not  clear,  but  is  mixed  with  water. 


Running  Locomotives. 


623 


To  use  a phrase  employed  by  practical  men,  the  priming  or  foaming  of 
the  boiler  may  be  known  by  the  “ flutter  ” of  the  gauge-cocks.  The  water 
will  also  rise  in  the  glass  water-gauge,  and  it  will  not  indicate  correctly 
the  quantity  of  water  in  the  boiler.  As  soon  as  there  ar2.  any  indications 
of  priming,  foaming,  or  that  water  is  working  into  the  cylinders,  the 
cylinder  cocks  should  be  opened  at  once,  otherwise  the  cylinders,  cylinder- 
heads,  or  pistons  may  be  broken.  The  throttle-valve  should  be  either 
partly  or  entirely  closed.  When  the  latter  is  done  the  foaming  will  in  most 
cases  cease  for  the  time,  so  that  the  engineer  can  tell  then  how  much 
“ solid  ” water  there  is  in  the  boiler.  When  the  flow  of  steam  from  the 
boiler  is  stopped  the  priming  usually  stops,  and  the  true  level  of  the  water 
will  be  shown  by  the  gauge-cocks  and  glass  water-gauge.  If  it  is  found 
that  there  is  too  much  water  in  the  boiler,  it  is  best  to  shut  off  the  feed, 
and  in  some  cases  the  blow-off  cock  should  be  opened.  The  latter  is, 
however,  attended  with  some  danger,  because  if  any  obstruction  should 
get  into  the  blow-off  cock,  or  it  should  stick  fast,  so  that  it  could  not  be 
closed,  all  the  water  would  escape  from  the  boiler,  and  with  a heavy  fire 
in  the  fire-box  there  would  be  great  danger  of  overheating,  and  thus  injur- 
ing the  boiler  or  of  “ burning  ” it,  as  it  is  ordinarily  termed.  In  that  event 
it  will  be  imperative  to  put  out  the  fire  at  once.  Another  method  of 
affording  relief,  if  a boiler  foams,  is  to  place  what  is  called  a surface-cock 
in  the  back  end  of  the  fire-box,  about  half  way  between  the  upper  and 
lower  gauge-cocks.  With  such  a cock,  the  water  can  be  blown  off  from 
the  surface  instead  of  from  the  bottom.  As  foaming  or  priming  is  often 
caused  by  oil  or  other  floating  impurities  on  the  surface,  they  can  be  blown 
out  of  the  boiler  with  this  arrangement,  whereas,  if  the  water  escapes  from 
the  bottom  of  the  boiler,  the  floating  impurities  will  always  remain  after 
it  is  blown  off.  A perforated  pipe,  which  extends  for  some  distance  along 
the  surface  of  the  water  inside  the  boiler,  is  sometimes  attached  to  the 
surface-cock,  so  that  the  water  which  is  blown  off  will  be  drawn  from  a 
number  of  points  along  the  surface.  If  it  is  essential  to  keep  the  train  in 
motion  when  the  boiler  foams,  it  is  a good  plan  to  place  the  reverse  lever 
in  full  gear  and  open  the  throttle-valve  very  little,  so  as  to  diminish  and 
equalize  the  flow  of  steam  into  the  cylinders. 

If  the  steam  is  rising  rapidly  when  foaming  begins,  it  will  be  well  to 
cool  the  boiler  off  by  opening  the  furnace  door  part  way.  This  means  of 
relief,  as  mentioned  before,  should,  however,  be  used  as  little  as  possible, 
because  there  is  always  danger  of  causing  the  tubes  or  other  parts  of  the 
boiler  to  leak,  by  either  heating  or  cooling  suddenly  or  rapidly.  If  the 


624 


Catechism  of  the  Locomotive. 


engine  primes  when  there  is  but  little  water  in  the  boiler,  and  at  a time 
when  the  steam  is  rising  rapidly,  it  may  sometimes  be  remedied  by  increas- 
ing the  amount  of  feed-water,  and  thus  partly  cooling  the  water  inside. 
The  use  of  pure  water,  careful  firing  so  as  to  keep  the  steam  pressure  regu- 
lar, feeding  the  boiler  so  that  the  level  of  the  water  will  be  nearly  uniform, 
and  then  starting  the  engine  carefully — that  is,  opening  the  throttle-valve 
gradually,  are  the  most  effective  means  in  practice  of  preventing  a locomo- 
tive boiler  from  priming. 

Question  829.  What  is  the  economical  effect  of  priming  on  the  con- 
sumption of  fuel  in  locomotives  ? 

Answer.  It  causes  a great  waste  of  heat,  first  by  the  escape  of  that  con- 
tained in  the  hot  water  which  passes  through  the  cylinders  and  which 
does  no  work,  and  second,  when  steam  is  mixed  with  a great  deal  of 
water,  it  will  not  flow  either  to  or  from  the  cylinders  as  quickly  or  easily 
as  dry  steam  will.  Consequently  the  initial  pressure  on  the  piston,  if  the 
engine  is  running  even  moderately  fast,  and  is  cutting  off  short,  will  not 
be  so  great  as  it  would  be  if  dry  steam  was  used.  Wet  steam  is  also  more 
difficult  to  exhaust  from  the  cylinders  than  that  which  is  dry,  and  there- 
fore the  back  pressure  on  the  piston  is  greater  when  the  boiler  primes  than 
when  dry  steam  alone  is  used. 

Question  830.  When  running  on  the  open  road,  what  should  the  loco- 
motive engineer  observe  ? 

Answer.  Either  he  or  the  fireman  should  constantly  watch  the  track  in 
front  of  them,  and  also  observe,  from  time  to  time,  whether  the  train  of 
cars,  especially  if  it  is  a long  one  which  he  is  handling,  is  in  good  con- 
dition. He  must  observe  every  signal  scrupulously,  and  should 
never  pass  one  until  he  is  sure  that  he  is  authorized  to  do  so. 
The  well-known  maxim,  “ Be  sure  you  are  right;  then  go  ahead,”  should 
be  changed  for  locomotive  engineers  to,  don’t  go  ahead  until  you  are 
sure  YOU  are  right.  Another  excellent  railroad  maxim  is,  “ when  in 
DOUBT  ALWAYS  CHOOSE  THE  SIDE  OF  SAFETY.” 

In  running  through  a curve,  the  speed  of  the  train  should  always  be 
moderated  in  proportion  to  the  sharpness  of  the  curve,  and  before  reach- 
ing it,  as  the  train  has  a tendency  to  continue  in  a straight  line,  and 
there  is  thus  danger  of  running  off  the  track.  The  higher  the  speed, 
of  course,  the  greater  is  the  resistance  which  is  required  to  prevent  the 
train  from  running  in  a straight  line,  and  consequently  the  greater  is  the 
strain  which  is  thrown  on  the  flanges  of  the  wheels  and  on  the  rails  and 
axles.  On  a curve  it  is  also  impossible,  usually,  to  see  further  than  a 


Running  Locomotives, 


625 


short  distance  ahead,  and  therefore,  if  the  train  is  running  very  fast,  it 
cannot  be  stopped  in  time,  should  there  be  any  obstruction  or  danger  on 
the  track. 

Question  831.  What  precautions  should  be  observed  in  running  over 
steep  grades  ? 

Answer.  On  approaching  an  ascending  grade  the  fireman  should  see 
that  the  fire  is  in  good  condition,  and  as  much  coal  should  be  put  on  it  as 
can  be  burned  to  advantage.  The  engineer  should  also  fill  the  boiler  as 
full  of  water  as  he  safely  can,  without  danger  of  priming,  and  should  heat 
this  water  as  hot  as  possible  without  blowing  off  steam  at  the  safety-valves. 
The  object  of  this  is  to  have  a supply  of  water  already  heated  before  reach- 
ing the  grade.  If,  as  often  happens  with  a heavy  train,  the  boiler  will  not 
make  as  much  steam  as  the  engine  consumes,  if  there  is  a large  supply  of 
hot  water  in  the  boiler  it  can  be  used  as  a reserve,  should  it  be  necessary 
to  do  so,  without  danger  of  injury  to  the  boiler  If  there  was  so  little 
water  in  the  boiler  that  it  would  be  dangerous  to  allow  it  to  get  lower, 
then  it  would  be  necessary  to  feed  cold  water  as  rapidly  as  the  hot  water 
escaped  in  the  form  of  steam.  When  the  engine  is  working  hard,  it  is 
often  impossible  to  heat  all  this  cold  water  as  fast  as  it  is  pumped  into  the 
boiler,  without  reducing  the  steam  pressure  until  there  is  not  sufficient 
power  to  pull  the  train.  If,  however,  there  is  a supply  of  hot  water  in  the 
boiler,  at  the  critical  point  on  the  grade,  where  the  engine  is  most  liable 
to  fail,  the  pump  or  injector  can  be  partly  shut  off,  and  thus  less  water  will 
be  fed  into  the  boiler,  and  the  steam  pressure  will  be  maintained  without 
danger.  Undoubtedly  it  is  better  to  feed  locomotive  boilers  uniformly,  if 
that  is  possible,  but  it  often  happens  that  a reserve  supply  of  hot  water  in 
the  boiler  enables  an  engine  to  pull  a train  up  the  most  difficult  place, 
whereas,  without  such  a supply,  the  locomotive  would  stick  fast.  As  the 
capacity  of  locomotives  is  rated  on  nearly  all  roads  by  the  number  of  cars 
they  can  “pull  up  the  hill,”  of  course  whatever  aids  them  at  the  critical 
point  increases  their  capacity.  This  fact  gives  engines  with  large  boilers 
much  advantage  over  those  with  small  ones. 

In  running  up  steep  grades,  allowance  should  always  be  made  for  the 
effect  of  the  inclination  of  the  track  upon  the  position  of  the  water  surface 
in  the  boiler,  and  also  the  fact  that  as  soon  as  the  throttle  valve  is  closed, 
and  steam  shut  off,  the  surface  of  the  water  will  be  considerably  lower 
than  when  the  engine  was  working  hard.  On  a grade  of  50  feet  to  a mile 
the  front  end  of  the  tubes  of  an  ordinary  locomotive  would  be  about  2 
inches  higher  than  the  back  end  of  the  crown-sheet.  If,  then,  on  work- 


626 


Catechism  of  the  Locomotive. 


ing  hard  up  such  a grade,  it  is  succeeded  by  another  of  equal  descent,  the 
front  end  of  the  tubes  would  be  2 inches  lower  than  the  back  end  of  the 
fire-box,  so  that  if  the  crown-sheet  was  covered  with  2 inches  of  water 
just  before  reaching  the  top,  it  would  be  exposed  to  the  fire  as  soon  as  the 
engine  reached  the  descent.  This  exposure  would  be  dangerous,  because 
not  only  would  the  water  be  2 inches  lower  over  the  crown-sheet,  but  it 
would  fall  considerably  more  when  the  throttle-valve  was  closed.  These 
considerations  will  show  the  danger  of  running  the  water  too  low  while 
ascending  steep  grades. 

In  pulling  trains  up  steep  grades,  especial  caution  should  be  exercised 
to  prevent  any  of  the  cars  from  breaking  loose  from  the  train,  because 
such  an  accident  may  cause  great  disaster. 

If  the  engine  is  not  equipped  with  an  automatic  cylinder  oiler,  as  soon 
as  the  top  of  the  grade  is  reached  the  fireman  should  oil  the  main  valves, 
because  it  can  only  be  done  when  steam  is  shut  off,  as  the  oil  will  not 
run  into  the  steam-chest  when  there  is  a pressure  of  steam  in  it ; and  as 
the  valves  are  always  subjected  to  the  severest  wear  while  pulling  up  a 
steep  grade,  the  valves  and  valve-faces  are  apt  to  become  dry.  As  satura- 
ted steam,  to  some  extent,  prevents  valves  from  cutting,  it  is  not  so  im- 
portant that  they  be  lubricated  while  the  engine  is  working  with  steam, 
but  as  soon  as  steam  is  shut  off  they  should  be  oiled,  otherwise  there  is 
danger  of  their  being  injured  by  their  friction  on  the  valve-seats. 

In  running  down  grades,  the  engineer  has  the  greatest  possible  cause 
for  using  every  precaution,  because  not  only  is  the  train  much  more  diffi- 
cult to  control,  but  usually  frequent  sharp  curves  prevent  a view  of  the 
track  for  any  considerable  distance  ahead.  He  should,  therefore,  watch 
the  track  in  front  of  him  with  the  greatest  vigilance,  so  as  to  be  ready  to 
give  the  requisite  signals  to  the  brakemen  to  apply  the  brakes,  or,  if  the 
engine  and  train  are  provided  with  continuous  brakes,  to  apply  the  latter, 
or  even  reverse  his  engine,  in  case  of  danger. 

Question  832.  What  must  be  done  on  approaching  a drawbridge  or  a 
crossing  of  another  railroad  at  the  same  level? 

Answer.  In  many  of  the  States  it  is  provided  by  law  that  all  trains 
must  come  to  a dead  stop  before  crossing  a drawbridge  or  another  railroad 
at  the  same  level.  When  interlocking  signals  are  provided  at  such  places 
it  is  not  considered  essential  to  stop,  but  the  engineer  should  then  be 
absolutely  certain  that  the  signals  indicate  that  the  line  is  clear,  and  he 
should  approach  such  places  with  his  train  under  sufficient  control,  so 
that  he  can  stop  it  in  case  of  danger.  The  train  should  under  no  circum- 


Running  Locomotives. 


627 


stances  run  up  to  such  points  until  a signal  has  been  given  that  the  line 
is  clear.  An  engineer  should  never  assume  that  the  signal  has  been  given, 
nor  take  another  person’s  word  for  it,  but  should  see  and  know  it  himself. 
In  some  conditions  of  the  weather,  and  with  the  light  falling  on  a signal 
in  certain  directions,  it  is  sometimes  difficult  to  determine  its  color  or 
form.  If  there  is  any  doubt  about  it,  the  testimony  of  another  person 
should  always  be  sought.  There  is  good  reason  for  believing  that  color- 
blindness— that  is,  an  incapacity  for  distinguishing  one  color  from  another, 
is,  if  not  a common  infirmity,  at  least  one  that  is  not  unknown.  It  is  cer- 
tain, too,  that  people  who  ordinarily  distinguish  colors  very  accurately  are 
subject  to  color-blindness  in  certain  conditions  of  health,  and  that  it  is 
sometimes  the  result  of  overwork  or  great  weariness ; and  a case  is 
recorded  of  a person  who  was  always  color-blind  after  a debauch.  There 
are,  therefore,  good  reasons  why  a locomotive  engineer  should  not  always 
place  too  implicit  confidence  in  what  he  “ sees  with  his  own  eyes,”  but  if 
he  has  any  doubt,  he  should  take  the  “benefit of  the  doubt,” which  should 
always  lead  him  to  take  the  side  of  safety. 

Question  833.  How  should  the  engine  and  train  be  managed  in  running 
into  a station  ? 

Answer.  First  of  all,  when  running  into  a station,  if  the  train  must 
stop  the  speed  should  be  checked  so  that  the  train  will  not  enter  with 
very  great  momentum.  Therefore,  at  a distance  varying,  according  to  the 
nature  of  the  grades  and  track,  the  steam  should  be  shut  off,  so  that  the 
speed  will  be  reduced  so  much  that  the  train  under  any  circumstances 
will  be  under  full  control.  It  is  always  better  to  enter  a station  at  too  low 
a speed  than  to  run  in  too  fast,  because  if  it  is  necessary,  more  steam  can 
always  be  admitted  to  the  cylinders  to  increase  the  speed  before  coming 
to  a stop ; whereas  it  is  not  so  easy  to  stop  the  train  if  it  is  running  too 
fast,  and  it  becomes  necessary  to  check  it  before  entering  the  station. 
This  will  sometimes  be  necessary,  because  it  may  readily  happen  through 
negligence  or  accident  at  stations  that  in  switching  cars  one  or  more  may 
be  left  standing  wholly  or  partly  on  the  track,  which  the  arriving  train 
must  run  over,  in  which  case  a collision,  with  its  terrible  consequences, 
may  be  unavoidable.  When  steam  is  shut  off  the  reverse  lever  should  be 
thrown  into  full  gear,  because  in  that  position  there  is  less  compression 
of  steam  in  the  cylinders,  and  therefore  not  so  much  liability  of  raising 
the  valve  from  its  seat. 

When  a train  is  equipped  with  continuous  brakes,  the  control  which 
they  usually  give  to  a locomotive  engineer  over  the  train  is  so  great  that 


628 


Catechism  of  the  Locomotive. 


he  is  apt  to  approach  stations,  crossings  or  drawbridges  at  a high  rate  of 
speed,  and  rely  on  such  brakes  to  stop  the  train.  This  practice  is  always 
attended  with  danger,  because  if  it  was  found,  on  getting  near  to  the  sta- 
tion, crossing  or  drawbridge,  that  the  track  was  not  clear,  and  that  it  was 
obstructed  by  a car  or  train,  or  the  draw  was  open,  if  the  engineer  should 
attempt  to  apply  the  brakes  and  from  some  cause  they  should  fail  to  work, 
as  sometimes  occurs,  then  a collision  or  other  disaster  would  be  inevitable, 
because  it  would  be  impossible  to  stop  the  train  with  the  ordinary  hand- 
brakes. For  this  reason  a locomotive  engineer  should  always  approach 
such  places  cautiously  and  with  his  train  under  sufficient  control,  so  that 
if  he  finds  there  is  danger  ahead  he  can  stop  the  train  with  the  ordinary 
means,  or  at  the  worst  by  reversing  the  engine.  Continuous  brakes  should 
always,  excepting  in  cases  of  imminent  danger,  be  applied  gradually,  so  as 
not  to  check  the  cars  with  a jerk  or  too  suddenly.  The  practice  of  open- 
ing the  engineer's  valve,  which  was  formerly  used  with  the  Westinghouse 
brake,  suddenly,  and  then  turning  it  back  again  as  quickly,  is  almost  sure 
to  produce  disagreeable  and  dangerous  shocks  to  the  cars.  This  cock 
should  be  opened  gradually,  so  as  to  check  the  cars  slowly  at  first.  The 
new  engineer’s  valve,  illustrated  and  described  in  answer  to  Question  631, 
is  arranged  so  that  air  can  be  turned  on  and  shut  off  quickly  without  pro- 
ducing disagreeable  shocks. 

Question  834,  What  must  be  attended  to  when  running  a locomotive 
at  night  ? 

Answer.  As  soon  as  it  begins  to  grow  dark,  the  head-light  must  be 
lighted  and  properly  trimmed,  and  the  proper  lamp  signals  placed  in  front 
of  the  engine,  if  the  rules  of  the  road  require  the  display  of  such  signals. 
A lamp  should  always  be  placed  in  the  cab,  so  as  to  throw  its  light  on  the 
steam-gauge,  but  not  into  the  engineer’s  face,  because  he  is  unable  to  see 
distant  signals  so  well  if  his  eyes  are  exposed  to  the  glare  of  a light  near 
him. 

At  night,  as  objects  which  are  passed  cannot  be  seen  distinctly,  it  is 
more  difficult  to  tell  the  speed  at  which  an  engine  is  running  than  it  is  in 
the  daytime.  An  engineer  should,  therefore,  consult  his  watch  frequently. 

Question  835.  What  must  be  attended  to  in  very  cold  weather? 

Answer.  Great  care  must  be  exercised  to  prevent  the  water  in 
the  pumps,  pipes,  and  in  the  tender,  from  freezing.  If  it  does  it 
will  be  almost  certain  to  break  the  pump  or  burst  the  pipes.  To  avoid 
this  the  heater  cocks  must  be  opened,  so  as  to  keep  the  water  in  the 
tender  warm.  In  excessively  cold  weather  the  engine  should  be  run  with 


Running  Locomotives. 


629 


greater  caution  than  at  other  times,  as  iron  is  then  more  brittle,  and  also 
more  liable  to  break,  owing  to  the  frozen  condition  and  consequent  solidity 
of  the  track. 

Question  836.  In  running  a locomotive  in  severe  snow  or  rain  storms , 
what  should  be  observed ? 

Answer.  Whenever  it  snows  the  pilot  or  cow-catcher  should  be  covered 
with  boards,  or,  better  still,  with  sheet  iron,  so  as  to  act  like  a snow  plow. 
Brooms  made  of  steel  wire  or  scrapers  should  be  placed  in  front  of  the 
front  wheels  of  the  engine,  so  as  to  clean  the  snow  from  the  rails.  The 
front  damper  on  the  ash-pan  should  be  kept  closed  so  as  to  exclude  the 
snow  from  the  ash-pan,  which  would  soon  fill  it  up,  and  in  this  way 
obstruct  the  draft.  If  the  fall  of  snow  is  very  heavy  or  it  blows  into  drifts, 
the  train  must  of  necessity  run  very  slowly,  and  even  if  a part  of  the  track 
is  clear  of  snow,  it  is  unsafe  to  run  fast  on  it,  as  there  would  be  danger  of 
throwing  the  engine  off  the  rails,  if  it  should  run  into  a heavy  drift  at  a 
high  speed. 

In  severe  rain  storms  bridges,  culverts,  and  such  portions  of  the  track 
as  are  liable  to  be  washed  away  should  be  approached  cautiously,  especially 
at  night.  In  both  snow  and  rain  storms,  and  also  in  fogs,  great  caution  is 
required,  owing  to  the  difficulty  of  seeing  signals. 

Question  837.  What  is  meant  by  a reserve  engine  or  “ helper  ? ” 

Answer.  A reserve  engine  is  a locomotive  which  is  not  employed  in 
hauling  a regular  train,  but  is  kept  as  a “ reserve  ” to  go  to  the  help  of  an 
engine  which  may  be  compelled  to  stop  on  account  of  an  accident  of  any 
kind,  or  to  assist  engines  in  moving  trains  up  heavy  grades,  or  is  used  in 
clearing  away  a wrecked  train,  rebuilding  bridges,  or  other  structures. 

Question  838.  What  must  be  observed  in  running  a reserve  engine? 

Answer.  As  no  special  arrangements  are  usually  made  in  preparing 
time-tables*  for  the  running  of  reserve  or,  as  they  are  usually  called  by 
railroad  men  “wild”  engines,  it  njay  very  probably  happen  that  it  will  be 
called  upon  to  assist  other  engines  when  the  road  is  not  clear,  and  there- 
fore its  engineer  must  consequently  be  on  the  lookout  for  signals  to  stop, 
which  are  often  given  suddenly.  He  must  switch  off  with  special  caution 
in  order  to  be  sure  to  keep  out  of  the  way  of  regular  trains  running  in  the 
opposite  direction  on  the  same  track.  When  he  reaches  the  train  or 
place  where  the  assistance  of  the  reserve  engine  is  needed,  he  must 
approach  it  slowly  and  carefully,  in  order  to  avoid  a violent  shock.  On 


* A time-table  is  a table  which  gives  the  time  when  each  train  shall  arrive  at  the  stations  it 
passes,  the  stations  at  which  it  shall  stop,  and  all  the  regulations  by  which  it  shall  be  run. 


630 


Catechism  of  the  Locomotive. 


the  return  from  the  assisted  train,  he  incurs  the  same  danger,  and  must 
pay  close  attention  to  any  signal  to  stop  made  to  him  by  any  opposite 
train  on  the  same  track,  and  also  on  his  part  warn  such  trains  by  the 
proper  signals. 

When  a train  is  run  with  two  engines,  both  in  front  of  it,  the  forward 
engineer  always  takes  the  management  of  the  train.  The  engineer  of  the 
hind  engine  must  be  guided  by  the  signals  of  the  one  on  the  forward 
engine.  In  starting,  the  forward  engine  must  be  set  in  motion  first  and 
then  the  one  behind  it.  In  stopping,  the  steam  must  be  shut  off  first  in 
the  hind  engine.  Likewise  in  decreasing  the  speed  during  the  trip,  the 
hind  engine  must  first  regulate  the  flow  of  steam.  If  these  precautions 
are  not  observed  the  forward  engine  may  easily  be  thrown  from  the  track 
by  the  faster  motion  of  the  hind  one.  When  there  are  two  engines  the 
air-brakes  should  always  be  operated  from  the  front  engine,  but  the  air- 
pump  on  the  rear  one  should  be  kept  running  to  assist  in  charging  the  brake 
reservoirs  with  compressed  air.  When  a train  is  assisted  by  a “helper,’' 
placed  behind  the  train,  and  therefore  pushing  it,  the  forward  engine 
must  likewise  be  set  in  motion  first,  and  steam  should  be  let  on  in  the 
hind  engine  only  after  a signal  has  been  given  by  the  engineer  of  the 
head  engine.* 

Question  839.  How  should  switching  engines  be  managed ? 

Answer.  In  pushing  and  switching  freight  cars  in  a station-yard,  they 
should  be  moved  carefully  and  severe  shocks  must  be  avoided,  as  the  cars, 
the  goods  with  which  they  are  loaded,  and  the  persons  employed  about 
them  may  be  injured  by  violent  concussions.  The  engineer  must  also 
follow  the  instructions  of  his  superior  strictly  and  cheerfully , and  should 
examine  patiently  and  observe  with  discretion  the  suggestions  of 
employees  who  are  not  his  superiors. 

In  this  service  it  is  also  of  special  importance  that  the  engineer  give  a 
distinct  signal  with  the  whistle  or  bell  before  every  movement  of  his 
engine,  in  order  to  warn  in  time  those  who  at  such  times  often  stand  on 
the  track  in  the  way  of  the  engine  or  cars,  or  the  persons  engaged  in  load- 
ing, cleaning  or  repairing  the  cars,  and  thus  give  them  time  to  get  out  of 
the  way.* 

Question  840.  In  firing  a locomotive , what  are  the  most  important 
ends  to  be  attained? 

Answer.  That  which  is  of  first  and  chief  importance  is  to  make  steam 


“ Katechismus  der  Einrichtung  und  Betriebes  der  Locomotive,’'  by  Georg  Kosak. 


Running  Locomotives. 


G31 


enough,  so  that  the  locomotive  can  pull  its  train  and  “make  time * sec- 
ond, it  should  make  the  requisite  quantity  of  steam  with  the  least  con- 
sumption of  coal,  and  third,  with  the  least  production  of  smoke,  although 
the  latter,  independent  of  the  economy  of  combustion,  is  considered  of  im- 
portance only  with  passenger  trains.  What  is  frequently  lost  sight  of  in 
considering  this  subject  is  the  fact  that  with  all  locomotives  it  often 
happens  that  it  is  a matter  of  extreme  difficulty  to  make  enough  steam  to 
do  the  work  required  of  the  engines.  When  a freight  train  is  struggling 
up  a grade  with  a heavy  train,  or  an  express  engine  is  obliged  to  make 
time  under  similar  conditions,  it  often  depends  entirely  upon  the  quantity 
of  steam  which  can  be  generated  in  the  boiler  in  a given  time  whether  the 
engine  will  fail  or  not.  In  firing,  therefore,  the  most  important  end  to  be 
aimed  at  is  often  simply  to  produce  the  largest  amount  of  steam  possible 
in  a given  time,  even  at  the  sacrifice  of  economy  or  by  producing  any 
quantity  of  smoke.  Any  means  of  economizing  fuel  or  of  smoke  preven- 
tion, which  reduces  the  steam-producing  capacity  of  boilers,  is  therefore 
quite  sure  to  be  abandoned  in  time. 

QUESTION  841.  How  can  a boiler  be  made  to  produce  the  largest  quan- 
tity of  steam  in  a given  time  ? 

Answer.  By  burning  the  greatest  quantity  of  fuel  possible  on  the  grate 
in  that  time.  This  can  be  done  by  keeping  the  grates  free  from  clinkers 
and  the  ash-pan  from  ashes,  and  then  distributing  the  coal  evenly  over 
the  grates  in  a layer  6 to  12  inches  thick.  The  thickness  of  the  layer 
which  will  give  the  best  results  will,  however,  vary  with  the  quality  of  the 
fuel,  and  must  be  determined  by  experience.  If  the  layer  is  too  thick, 
not  enough  air  will  pass  through  it  to  burn  the  coal.  If  it  is  too  thin,  then 
so  much  air  will  pass  through  that  the  temperature  in  the  fire  will  be 
reduced.  The  rapidity  of  combustion  will  also  be  promoted  by  breaking 
up  the  coal  into  lumps  the  size  of  a man’s  fist  or  smaller.  If  fine  coal  is  used 
it  should  be  wet,  otherwise  it  will  be  carried  into  the  flues  by  the  blast 
before  it  is  burned,  or  caked,  or  even  before  it  reaches  the  grate.  Experience 
will  indicate  the  amount  of  air  which  can  advantageously  be  admitted 
above  the  fire  in  order  to  secure  the  maximum  production  of  steam.  The 
best  size  of  the  exhaust  nozzles  and  the  position  of  the  petticoat-pipe  must 
also  be  determined  by  experience.  It  will  usually  be  found,  however,  that 
if  enough  air  is  admitted  above  the  fire  to  prevent  smoke,  it  will  reduce 
the  maximum  amount  of  steam  which  can  be  generated  in  a given  time. 
The  fire  should  also  be  fed  regularly  and  with  comparatively  small  quan- 

* The  term  make  time  means  to  run  at  the  speed  indicated  on  the  time-tabl 


632 


Catechism  of  the  Locomotive. 


tities  of  fuel  at  a time,  although  if  the  feeding  is  too  frequent  there  is  more 
loss  from  the  cooling  effect  which  results  from  the  frequent  opening  of  the 
furnace  door  than  is  gained  from  the  regularity  of  the  firing.  In  this,  too, 
a fireman  must  consult  experience  to  guide  him. 

Question  842.  How  can  a loco?notive  be  fired  with  the  least  consump- 
tion of  coal? 

Answer.  Two  systems  of  firing  are  practised  in  this  country,  one  known 
as  the  “ banking  system  ” and  the  other  the  “ spreading  system.” 
When  the  banking  system  is  employed,  the  coal  is  piled  up  at  the  back 
part  of  the  fire-box,  as  shown  in  fig.  476,  and  slopes  down  towards  the 
front  of  the  grate,  where  the  layer  of  coal  is  comparatively  thin  and  in  an 
active  state  of  incandescence.  The  heap  of  coal  behind  is  gradually 
coked  by  the  heat  in  the  fire-box,  and  the  gases  are  thus  expelled.  Open- 
ings in  the  furnace  door  admit  air,  which  mingles  with  the  escaping  gases 
which  then  pass  over  the  bright  fire  in  front,  and  are  thus  supposed  to  be 
consumed.  When  the  “ bank  ” of  coal  behind  becomes  thoroughly  coked, 
it  is  pushed  forward  on  the  bright  fire  and  fresh  coal  is  again  put  on  be- 
hind to  be  coked.  This  system  of  firing  is  practised  on  some  roads  with 
good  results,  but  it  is  doubtful  whether  it  could  be  used  successfully  with 
coal  which  cakes  and  clinkers  badly. 

The  spreading  system  is  most  commonly  employed  in  the  Western 
States,  where  the  coal  contains  a great  deal  of  clinker.  When  this  is 
practised,  the  coal  is  spread  evenly  over  the  whole  of  the  grate  in  a thin 
layer,  and  its  success  and  economy  depend  upon  the  regularity  and  even- 
ness with  which  this  layer  of  coal  is  maintained  and  the  fire  fed.  The 
thickness  of  the  coal  must  be  adapted  to  the  working  of  the  engine. 
When  it  is  working  lightly,  the  layer  of  coal  should  be  thin,  but  when 
the  engine  is  pulling  hard  the  layer  of  coal  must  be  thicker,  otherwise  the 
violent  blast  may  lift  the  coal  off  the  grates.  The  success  of  this  system, 
as  was  explained  in  answer  to  Question  739,  depends  upon  the  manner  in 
which  the  thickness  of  the  fire  is  regulated,  on  the  admission  of  the  proper 
amount  of  air  above  the  fire,  and  on  the  frequency  with  which  the  fire  is 
supplied  with  coal.  When  this  system  of  firing  is  employed  not  more  than 
two  shovelsful  of  coal  should  be  put  into  the  fire-box  at  once,  and  if  the 
engine  is  not  working  hard,  one  or  even  less  will  be  sufficient.  The  fire- 
man must,  however,  determine  by  experience  the  thickness  of  fire,  amount 
of  air  which  should  be  admitted  and  the  frequency  of  firing  which  will 
give  the  best  results  in  practise.  Doubtless  these  will  vary  with  different 
kinds  of  fuel  and  the  construction  of  engines.  Usually  the  greatest 


Running  Locomotives. 


633 


obstacle  in  the  way  of  producing  good  results  is  the  fact  that  firemen 
wou'd  rather  “take  things  easy”  than  exercise  that  diligence  and  observa- 
tion which  will  alone  insure  success  in  any  occupation. 

Question  843.  How  can  smoke  be  most  effectually  prevented? 

Answer.  The  means  of  preventing  smoke  were  very  fully  explained  in 
answer  to  Questions  752  and  753.  It  may  be  said  briefly  that  this  can  be 
done  only  by  properly  regulating  the  supply  of  air  which  is  admitted  to 
the  fire.  The  means  of  doing  this  have  already  been  explained. 

Question  844.  What  method  of  firing  is  employed  when  anthracite 
coal  is  used? 

Answer.  The  spreading  system  alone  is  then  used. 

Question  845.  How  may  the  rules  which  firemen  should  observe  when 
bituminous  coal  is  used  be  briefly  stated? 

Answer.  (1)  Keep  the  grate,  ash-pan  and  tubes  clean.  (2)  Break  the 
coal  into  small  lumps.  (3)  Fire  often  and  in  small  quantities.  (4)  Keep 
the  furnace  door  open  as  little  as  possible.  (5)  Consult  the  steam-gauge 
frequently,  and  maintain  a uniform  steam  pressure,  and  if  necessary  to 
reduce  the  pressure  do  it  by  closing  the  ash-pan  dampers  rather  than  by 
opening  the  furnace  door. 

QUESTION  846.  On  arriving  at  a station  where  a train  stops  longer 
than  a few  minutes , what  should  the  locomotive  engineer  and  fire  in  an  attend 
to? 

Answer.  The  engineer  should  examine  thoroughly  all  the  parts  of  his 
engine,  as  has  been  heretofore  explained.  He  should  especially  examine 
all  the  journals  and  wearing  surfaces' to  see  whether  they  are  hot.  This 
he  can  discover  by  feeling  them.  If  any  of  them  have  become  very  much 
heated,  they  must  be  cooled  by  throwing  cold  water  on  them,  and  then 
thoroughly  oiled.  The  working  parts  should  be  thoroughly  lubricated,  as 
already  explained. 

The  fireman  should  examine  the  tank  and  see  whether  it  is  necessary 
to  take  in  a fresh  supply  of  water.  He  should  then  examine  the  grates 
and  ash-pan,  and  clean  the  cinders  and  clinkers  from  the  former,  and  the 
ashes  from  the  latter.  Neglecting  to  clean  the  ash-pan  may  result  in 
melting  and  destroying  the  grate-bars,  and  by  obstructing  the  admission 
of  air  to  the  grates,  the  ashes  prevent  the  combustion  from  being  as  com- 
plete as  it  would  otherwise  be.  With  some  kinds  of  fuel  it  is  necessary 
to  clean  the  tubes  frequently,  which  must  often  be  done  at  stations  where 
the  train  stops. 

During  the  stop,  as  thorough  an  inspection  of  the  engine  should  be 


634 


Catechism  of  the  Locomotive. 


made  by  the  engineer  and  fireman  as  the  time  will  permit ; but  any  un- 
necessary waste  of  time  must  be  avoided,  and  the  firing  should  be  so 
managed  that  nothing  need  be  done  about  it  during  the  halt  at  the  sta- 
tion. On  starting  again  the  same  precautions  should  be  exercised  as  on 
making  the  first  start. 

Question  847.  After  reaching  the  end  of  its  run,  how  should  an  engme 
be  cleaned  and  repaired? 

Answer.  Before  reaching  the  last  station  the  firing  should  be  so  man- 
aged that  there  will  be  as  little  fire  as  possible  remaining  in  the  fire-box 
at  the  end  of  the  run.  After  the  arrival  the  engine  should  be  run  over  a 
pit  which  is  usually  provided  for  the  purpose,  and  the  fire  should  be  raked 
out  of  the  fire-box  by  dropping  the  drop-door,  if  there  is  one  to  the  grate, 
or  turning  the  grate-bars  edgewise,  or  withdrawing  one  or  more  of  them, 
if  it  is  necessary  to  do  so.  In  this  way  the  fire  will  fall  into  the  ash-pan, 
from  which  it  can  easily  be  raked.  After  all  the  fire  is  withdrawn,  the 
dampers  and  furnace  door  should  be  closed  so  as  not  to  allow  the  cold  air 
to  cool  the  fire-box  and  tubes  too  rapidly. 

In  order  to  keep  the  boiler  clean — that  is,  as  free  as  possible  from  sand, 
sediment  or  incrustation,  it  is  necessary  to  blow  it  out  frequently,  if  the 
water  which  is  used  contains  much  solid  or  incrustating  matter.  With 
“ bad  water  ” the  boiler  should  be  blown  out  as  often  as  possible.  On 
some  roads  this  is  done  after  each  trip.  In  blowing  a boiler  out,  the 
blow-off  cocks  must  be  left  open,  and  after  all  the  water  has  escaped  the 
engine  should  be  left  to  stand  until  it  is  cooled  off.  If  there  is  any  con- 
siderable accumulation  of  mud  or  sediment  the  hand-holes  at  the  bottom 
of  the  fire-box  and  the  cover  to  the  mud-drum  should  be  taken  off,  and 
as  much  of  the  mud  removed  as  can  be  scraped  out  through  those  aper- 
tures. A hose-pipe  attached  to  the  hose  of  a force  pump  should  then  be 
inserted  through  these  same  openings,  and  a strong  stream  of  water  forced 
into  the  boiler.  By  this  means  much  of  the  loose  mud  and  scale  will  be 
washed  out.  The  oftener  this  is  repeated,  of  course,  the  cleaner  can  a 
boiler  be  kept.  If  a large  amount  of  incrustation  or  mud  has  accumulated 
about  the  tubes,  some  or  all  of  them  must  be  taken  out,  so  as  to  be  able 
to  remove  the  dirt. 

After  an  engine  is  blown  out,  under  no  circumstances,  excepting  abso- 
lute necessity,  should  it  be  filled  with  cold  water  until  it  is  cooled  off.  It 
should  be  remembered  that  any  sudden  change  of  temperature  in  a boiler 
subjects  it  to  very  great  strains  and  incurs  the  danger  of  cracking  the  fire- 
box plates,  or  causing  the  tubes  to  leak. 


Running  Locomotives. 


635 


The  tender  should  also  be  cleaned  of  the  mud  which  settles  in  it  from 
time  to  time,  but  it  is  not  necessary  to  do  this  as  often  as  it  is  to  clean 
the  boiler.  The  strainers  in  the  tank  over  the  water-supply  pipes  should 
be  examined  and  cleaned  frequently.  • All  the  plates  and  flues  should  have 
the  soot  which  sticks  to  them  thoroughly  cleaned  off. 

Although  the  cleaning  of  the  boiler  and  the  grates  is  usually  committed 
to  a special  set  of  men,  yet  the  locomotive  engineer  should  examine  them 
personally  to  see  that  it  is  properly  done.  He  should  pay  attention  to  the 
condition  of  the  grate,  and  see  whether  it  is  level  and  smooth.  As  soon 
as  one  or  more  of  the  bars  are  bent  crooked,  they  usually  burn  out.  If 
one  of  the  bars  is  burned  out  the  fire  falls  through  the  hole  that  it  leaves 
into  the  ash-pan,  and  then  the  fire  under  the  grate  will  heat  it  red  hot, 
and  finally  may  melt  or  “ burn  ” every  bar.  Every  grate-bar  which  is  only 
a little  damaged  or  bent  must,  therefore,  be  removed  as  quickly  as  possible 
and  replaced  with  a new  one.  An  opening  in  the  grate  larger  than  the 
spaces  between  the  bars  allows  a superfluous  amount  of  cold  air  to  enter 
the  fire-box,  and  diminishes  the  steam-generating  capacity  of  the  boiler. 

As  soon  as  the  engine  is  run  into  the  engine-house,  the  cylinder-cocks 
should  be  opened  and  left  open  while  it  is  standing  stiff,  so  that  the  con- 
densed water  can  escape.  All  superfluous  grease  which  has  escaped  from 
the  wearing  surfaces  and  the  dust  or  mud  which  adheres  to  the  engine 
should  be  wiped  off  with  cotton  waste  or  rags.  This  is  usually  done  by 
men  employed  for  the  purpose.  While  they  are  doing  this,  they  should 
examine  every  part  thoroughly  and  observe  whether  it  is  in  good  condition, 
and  if  any  defects  are  found  they  should  be  reported  to  the  proper  person 
whose  business  it  is  to  have  them  repaired.  As  the  faithfulness  and  skill 
of  a fireman  are  often  estimated  by  the  good  or  bad  condition  of  his 
engine,  he  should,  if  for  no  other  reason,  take  pains  to  keep  it  clean  and 
everything  in  as  good  condition  as  possible. 

If  the  engine  is  taken  to  pieces  in  order  to  be  thoroughly  repaired,  the 
engineer,  if  he  does  not  help  to  do  this,  should  watch  carefully  the  taking 
it  apart,  and  the  putting  it  together  again,  as  in  this  way  he  can  become 
thoroughly  familiar  with  the  construction  of  the  machine  or  machines  he 
runs. 

Question  848.  What  precaution  must  be  taken  to  prevent  the  water  in 
a locomotive  from  freezing,  if  it  is  laid  up  f 

Answer.  In  very  cold  weather,  if  engines  are  laid  up  for  any  consider- 
able time,  no  water  must  be  left  in  the  tender,  boiler,  or  any  of  the  pipes. 
If,  however,  the  engine  must  be  soon  used,  and  it  is  impracticable  to  let 


636 


Catechism  of  the  Locomotive. 


the  water  out  of  the  boiler  and  tender,  then,  if  exposed  to  the  cold,  a light 
fire  must  be  kept  in  the  boiler  sufficient  to  make  steam  enough  to  warm 
the  water  in  the  tender.  The  water  should,  however,  be  drawn  out  of  the 
pumps,  injectors,  and  the  feed  and  -supply  pipes.  This  can  be  done  by 
opening  the  pet-cocks,  and  closing  the  tender-valves  and  uncoupling  the 
hose,  which  will  allow  the  water  in  the  supply  pipes  to  run  out.  By  run- 
ning the  engine  a few  revolutions  the  pumps  will  then  be  emptied.  The 
pipes  and  the  pumps  can  also  be  prevented  from  freezing  without  un- 
coupling the  hose,  if  the  tender-valves  are  closed  and  the  pet-cocks  opened, 
and  steam  is  then  admitted  into  the  supply  pipes  by  the  heater-cocks. 
This  forces  part  of  the  water  which  is  in  the  pumps  out  of  the  pet-cocks 
and  warms  the  rest.  This,  however,  requires  constant  watchfulness  to 
prevent  freezing,  and  in  excessively  cold  weather,  if  the  engine  must  lay 
up  for  any  considerable  time,  it  is  always  best  to  empty  the  pumps  and 
pipes. 


CHAPTER  XXXV. 


RESPONSIBILITY  AND  QUALIFICATIONS  OF  LOCOMOTIVE  ENGINEERS.* 

Question  849.  What  are  the  dangers  to  which  the  engineer  and  the 
fireman  are  exposed  by  their  work  on  the  engine  ? 

Answer.  Engineers  and  firemen  are  not  only  exposed  to  great  bodily 
injury  or  even  death  by  every  accident  which  may  happen  to  their  engine, 
but  unless  they  are  very  careful  to  preserve  their  health  it  is  quickly 
destroyed  by  the  constant  changes  of  the  weather  to  which  their  position 
exposes  them,  and  also  by  the  effect  of  the  heat  of  the  fire  and  by  the 
smoke  by  which  they  are  often  surrounded. 

In  order  to  protect  themselves  in  a measure  from  the  injurious  effects 
of  change  of  weather,  smoke,  cold,  etc.,  frequent  bathing  and  cleansing  of 
the  skin  are  very  beneficial,  and  also  the  wearing  of  a woolen  undershirt 
next  the  skin  at  all  seasons. 

The  gases  of  coal  which  pour  out  of  the  furnace  door,  if  it  is  opened 
when  the  throttle  is  closed,  have  an  especially  injurious  effect  on  the 
throat,  lungs,  etc.  They  should  see  to  it,  therefore,  that  the  blower  is 
always  started  before  the  fire-door  is  opened,  in  order  that  these  injurious 
gases,  which  have  collected  during  a halt,  may  be  drawn  forward  and  up 
the  chimney  by  the  draft. 

The  steady,  loud  clatter,  which  the  engine  makes  while  running,  has  an 
injurious  influence  on  the  nervous  system.  The  engineer  should  there- 
fore endeavor  to  lessen  these  shocks  of  the  engine  as  far  as  possible  by 
keeping  watch  over  it  and  keeping  its  parts  accurately  adjusted.  In  order 
to  keep  himself  fresh  and  strong  in  his  service,  which  is  extremely  ex- 
haustive to  body  and  mind,  the  engineer  should  try  to  strengthen  himself 
by  regular,  temperate  living,  and  eating  abundant  nourishing  food.  The 
common  use  of  strong  drinks,  which  undermines  the  mental  and  physical 
strength  of  men,  should  be  avoided  by  a person  occupying  the  exhaustive 
and  responsible  position  of  a locomotive  engineer.  If  in  ordinary  life  a 
drunken  man  is  unfit  for  any  simple  work,  how  shall  a drunken  engineer 


* A portion  of  this  chapter  is  a translation  from  Professor  Georg  Kosak’s  “ Katechismus 
der  Einrichtung  und  Betriebes  der  Locomotive.” 


638 


Catechism  of  the  Locomotive. 


or  fireman  undertake  the  difficult  management  of  so  great,  so  delicate, 
and  so  costly  a machine  as  a locomotive  ? How  can  hundreds  of  men 
quietly  trust  their  lives  and  limbs  to  such  a man,  whom  no  one  can  help 
despising  ? Rightfully,  therefore,  conscientious  railroad  managers  place 
the  greatest  stress  on  the  sobriety  of  the  engineers  and  firemen,  and 
instantly  discharge  from  their  service  those  who  give  themselves  up  to  a 
passion  for  drink. 

Owing  to  the  demands  which  their  daily  labor  makes  upon  their  strength 
and  endurance,  locomotive  engineers  should  be  careful  not  to  increase 
the  drain  by  dissipation,  irregular  hours,  or  overwork.  There  seems  to 
be  something  about  the  power  of  endurance  of  the  human  frame  analogous 
to  the  capacity  of  a bar  of  iron  or  steel  to  resist  strains.  So  long  as  the 
strains  do  not  exceed  the  elastic  limit — that  is,  if  the  bar  recovers  its 
original  length  when  the  strain  is  removed,  it  will  bear  millions  of  such 
strains  without  becoming  weaker ; but  if  it  is  strained  so  hard  that  it  is 
permanently  stretched,  then  comparatively  few  applications  of  the  force 
will  rupture  the  bar.  In  a similar  way,  if  the  strain  or  fatigue  which  a 
man  endures  is  no  more  than  he  will  recover  from  after  the  ordinary  rest, 
he  can  endure  an  almost  unlimited  number  of  such  strains,  but  if  the 
fatigue  exceeds  his  “elastic  limit,”  then  he  soon  becomes  permanently 
injured  thereby.  It  often  happens  that  an  excessive  amount  of  work  is 
unavoidable,  but  when  it  can  be  avoided  it  should  be  by  those  who  wish 
to  preserve  their  health  and  strength. 

In  order  to  save  themselves  from  great  injuries,  engineers  and  firemen 
should  always  act  with  the  greatest  caution,  and  never  rush  carelessly  into 
danger.  They  should  never  adopt  the  principle  of  foolhardy  and  thought- 
less people,  who  by  the  consciousness  of  continual  danger  fall  into  the 
habit  of  carelessly  “ trusting  to  their  luck,”  etc.  On  the  contrary,  they 
should  always  face  the  danger  with  their  eyes  open  and  with  the  greatest 
conscientiousness.  Many  try  to  show  great  courage  by  scorning  the 
danger,  and  some  such  even  wish  to  meet  a little  in  order  to  be  able  to 
show  that  they  are  not  afraid.  These  should  bear  in  mind  that  they  have 
a great  responsibility  laid  upon  them,  and  that  it  is  not  alone  their  own 
well-being  or  life  which  is  at  stake  in  case  of  any  mishap,  but  that  by  their 
careless  behavior  they  may  wound  or  kill  the  helpless  people  who  are 
committed  to  their  care,  cause  incalculable  misery  by  jobbing  families  of 
their  sole  support  and  of  their  children,  and  bring  great  sorrow  and 
mourning  to  their  fellow  men.  The  thought  of  the  curse  and  the  despair 
of  the  survivors  may  give  sleepless  hours  even  to  a locomotive  engineer 


Responsibility  and  Qualifications  of  Engineers. 


639 


who  knows  himself  to  have  been  without  any  fault  regarding  an  accident; 
how  much  more  must  it  be  with  him  who  cannot  give  himself  this  assur- 
ance? There  are  not  wanting  instances  in  which  the  engineer  who  caused 
such  an  accident  by  his  thoughtlessness,  driven  to  despair  by  his  own 
heavily-burdened  conscience,  went  miserably  to  ruin. 

Question  850.  What  should  a locomotive  engineer  and  fireman  do  to 
preserve  their  health  ? 

Answer.  The  following  excellent  suggestions  * to  workingmen  for  the 
prevention  of  sickness  may  be  followed  by  all  locomotive  engineers  and 
firemen,  to  their  own  great  advantage  and  that  of  their  families. 

They  include,  first,  attention  to  home  surroundings,  and  second  to 
personal  habits. 

In  regard  to  the  first,  one  of  the  earliest  physicians,  Hippocrates,  said 
that  the  essentials  of  health  were  pure  air,  pure  water,  and  a pure  soil. 
Your  home  should,  above  all  things,  be  free  from  damp.  It  should  not 
be  built  upon  made  land  or  where  it  can  be  flooded  by  rains  or  by  a rise 
of  tide.  Dampness  is  a source  of  consumption,  rheumatism,  croup, 
diphtheria,  and  other  diseases.  The  nearer  your  living  rooms  are  to  the 
ground,  the  more  danger  there  is  of  damp.  It  is  better  to  occupy  an  attic, 
where  you  can  get  the  sun  and  the  air  than  a basement. 

Again,  new  houses  are  liable  to  be  damp  from  the  evaporation  from  the 
plaster  and  mortar,  which  contain  a large  amount  of  water.  A Spanish 
proverb  says  of  new  houses,  “ The  first  year  for  your  enemies,  the  sec- 
ond year  for  your  friends,  and  the  third  you  may  live  there  yourself." 
Again,  cellar  air  is  unwholesome ; and  this  is  another  reason  why  base- 
ment rooms  are  bad.  It  is  very  unwise  to  store  vegetables  in  cellars,  or 
anything  that  will  cause  impurity  of  the  air. 

Pure  air  is  the  most  vital  thing  of  all.  One  may  live  without  proper 
food  and  drink,  and  on  a damp  soil  with  impunity,  but  foul  air  slays  like 
a sword.  Every  person  needs  pure  air  to  breathe.  Each  time  we  empty 
our  lungs  a certain  amount  of  impure  air  is  thrown  off.  Thousands  die 
yearly  for  lack  of  pure  air.  It  is  free  to  all ; it  costs  nothing.  Open  the 
window,  and  it  flows  in  abundance  to  the  beggar  as  to  the  millionaire, 
bringing  health  and  life  to  all — if  only  people  would  not  shut  and  bar  it 
out  in  their  blind,  stupid  ignorance. 

What  is  it  that  makes  most  people  sick  ? Eating  too  much  and  too  fast ; 
drinking  too  much  ; want  of  fresh  air  ; want  of  sunlight ; want  of  exercise ; 
want  of  cleanliness.  Few  persons  die  of  starvation — many  do  of  gluttony. 


* Published  by  the  Citizens’  Sanitary  Association  of  Brooklyn,  N.  Y. 


640 


Catechism  of  the  Locomotive. 


Bathe  as  often  as  you  can.*  Remember  “cleanliness  is  next  to  godli- 
ness,” and  a foul  body  usually  means  afoul  mind.  Keeping  the  pores  of 
the  skin  open  is  a prime  element  of  health.  How  carefully  we  groom 
our  horses!  and  is  not  a man’s  health  as  precious  as  that  of  a horse? 

Let  your  wife  and  children  have  as  much  out-door  exercise  as  they  can 
get.  It  will  be  a change,  and  won’t  do  the  least  harm. 

Don’t  sit  in  damp  clothes  if  you  come  home  wet.  If  you  feel  chilled 
and  cold,  soak  your  feet  in  a pail  of  hot  water,  then  go  to  bed  and  pile  on 
the  clothes  till  you  sweat,  and  you  will  escape  catching  cold.  In  such 
cases,  hot  tea,  or  coffee,  or  soup  is  better  than  whiskey  to  warm  you.  In 
cold  countries  tea  is  preferred  to  any  drink.  Liquor  should  never  be 
taken  by  a sick  person,  unless  by  a doctor’s  orders. 

Clothes  should  fit  loosely,  should  be  light,  warm,  and  porous,  should  be 
adapted  to  the  season  as  to  color,  should  be  frequently  changed,  and 
should  be  scrupulously  clean. 

In  cooking,  use  the  frying  pan  as  little  as  possible ; greasy  food  is  very 
unwholesome.  Avoid  too  much  pork  and  liquors. 

Eat  slowly,  chewing  the  food  well,  and  drink  very  little  liquid  of  any 
kind  while  eating.  Tea  is  not  food,  and  too  much  of  it  is  drunk  by  many 
persons,  especially  women  and  children.  Eat  hominy  in  preference,  and 
give  children  plenty  of  milk.  Beans  are  very  nutritious. 

Don’t  shut  every  cranny  and  crack  to  keep  out  the  air  from  the  rooms, 
but  let  the  windows  stay  open  for  a time. 

Don’t  forbid  the  blessed  sun  from  entering  your  windows.  Don’t  stay 
in  a house  that  has  a bad  smell  in  it. 

Don’t  live  in  dark,  gloomy,  close  rooms  if  you  can  get  sunny,  cheery  ones. 

Remove  all  garbage  and  refuse  as  soon  as  possible  from  your  houses. 

Have  the  walls  and  ceiling  whitewashed  or  kalsomined  once  or  twice 
every  year. 

In  looking  for  apartments,  always  strive  to  secure  a well-ventilated 
bedroom.  Air  the  room  and  bed-clothing  every  morning.  Keep  as  few 
clothes,  not  in  use,  as  possible  in  the  bedroom,  and  do  not  sleep  in  any 
garment  which  is  worn  by  day. 

Question  851.  What  requirements  and  duties  should  every  locomotive 
engineer  fulfil? 

Answer.  Every  locomotive  engineer  should  fulfil  the  following  require- 
ments and  duties : 

* If  a bath  tub  is  not  available,  a damp  or  wet  towel— the  coarser  the  better— rubbed  briskly 
all  over  the  body  every  morning  is  an  excellent  substitute  for  a bath. 


Responsibility  and  Qualifications  of  Engineers. 


641 


1.  He  should  have  an  exact  knowledge  of  the  engine  entrusted  to  him, 
and  a general  knowledge  of  the  nature  and  construction  of  steam-engines 
S'enerally.  Likewise,  he  should  be  perfectly  familiar  with  the  manage- 
ment of  the  boiler,  the  running  of  the  engine,  and  the  way  of  keeping  the 
working  parts  in  good  condition ; also  with  the  forms  and  peculiarities  of 
the  line  of  road  on  which  he  runs,  the  rules  which  govern  the  running  of 
trains  and  with  the  signal  system  adopted. 

2.  Health  and  bodily  strength  he  must  have  in  abundant  measure  in 
his  position,  which  is  exhausting  and  in  which  he  is  exposed  to  all  sorts 
of  weather. 

3.  He  should  have  at  least  a good,  plain  common-school  education, 
and  be  ready  at  reading,  writing  and  arithmetic. 

4.  He  should  always  carry  out.  exactly  and  cheerfully  the  regulations  of 
the  service,  or  the  instructions  given  him  by  special  orders  from  the 
officers  over  him. 

5.  Faithfulness,  frankness  and  honesty , which  characterize  an  upright 
man  in  ordinary  life,  and  also  the  strictest  temperance  in  the  use  of  strong 
drink,  he  should  possess  in  a high  degree  in  his  very  responsible  position. 

6.  He  should  have  acquired  a certain  degree  of  skill  in  putting  together 
and  taking  apart  locomotives,  and  also  in  repairing  separate  parts  of  them. 
It  is  desirable  that  he  should  always  be  present  when  his  own  engine  is 
taken  apart,  put  together,  or  repaired,  in  order  that  he  may  acquire  a 
thorough  knowledge  of  its  condition  and  learn  to  understand  properly 
the  importance  of  its  various  parts. 

7.  In  caring  for  his  engine,  he  must  preserve  perfect  cleanliness  and 
order,  and  in  using  fuel  he  should  manifest  the  greatest  care  and  rigid 
economy. 

8.  Wheneverthere  is  danger,  coolness  and  self-possession  are  indispen- 
sably necessary,  and  any  thoughtlessness  or  recklessness  is  to  be  strictly 
avoided. 

9.  Toward  his  superior  officers  his  behavior  should  be  respectful  and 
obliging;  towards  those  under  him,  patient  and  kindly,  and  at  all  times 
he  should  avoid  profanity  and  all  intemperate  language,  and  obey  the 
Ten  Commandments.  He  should  endeavor,  as  far  as  possible,  to  instruct 
the  fireman  who  accompanies  him  and  make  him  familiar  with  the  con- 
struction and  management  of  the  engine,  and  should  see  that  he  does  his 
work  strictly  in  accordance  with  his  instructions. 

It  is  the  firemans  duty  to  follow  the  engineer’s  instructions  strictly,  and 
in  case  of  any  sudden  disability  of  the  engineer  he  must  stop  the  engine 


642 


Catechism  of  the  Locomotive. 


in  accordance  with  the  instructions  given  him,  and  then  give  the  proper 
signals  for  help,  until  another  engineer  arrives.  In  the  meanwhile  the 
engine  is  to  be  kept  at  a halt  with  all  the  usual  precautions. 

10.  The  engineer  should  try  to  keep  himself  informed  of  the  progress 
and  improvement  of  locomotives  by  reading  suitable  books  and  technical 
periodicals,  and  when  possible  acquire  some  skill  in  geometrical  and 
mechanical  drawing,  in  order  to  accustom  himself  to  accurate  work  and 
sound  and  systematic  thinking. 

Question  852.  What  studies  should  mechanics , locomotive  engineers 
and  firemen  take  up,  and  what  technical  books  should  they  read? 

Answer.  As  already  stated,  they  should  know  how  to  read  and  write 
their  own  language,  and  understand  arithmetic  and  have  some  knowledge 
of  geography.  Every  locomotive  runner  and  fireman  has  a good  deal  of 
spare  time,  a part  of  which  he  can  devote  to  study,  and  all  of  them,  even 
if  they  have  not  had  the  advantage  of  early  education,  could  by  industry 
and  perseverance  acquire  a knowledge  of  “ reading  writing,  and  cipher- 
ing.” The  assistance  of  a good  teacher  should  always  be  procured,  if 
possible.  With  so  much  knowledge,  some  book  on  natural  philosophy 
can  be  read  to  advantage,  and  then  some  book  on  mechanics.  It  should 
always  be  remembered,  however,  that  the  mere  buying  of  books  contrib- 
utes very  little  knowledge  to  the  owner.  It  is  the  reading  and  understand- 
ing  them  which  “ increases  knowledge.”  Before  buying  books  it  will  be 
well  to  ascertain  from  persons  capable  of  judging  of  their  character, 
whether  they  are  worth  buying,  as  there  is  more  difference  in  the  quality 
and  character  of  books  than  there  is  in  almost  any  other  commodity 
which  is  sold.  Many  which  are  written  and  published  are  not  worth  buy- 
ing or  are  unsuited  to  the  wants  of  the  purchaser,  while  a really  good  book 
— and  there  are  many  such — is  a treasure. 


CHAPTER  XXXVI. 


ACCIDENTS  TO  LOCOMOTIVES. 

Question  853.  What  are  the  most  serious  accidents  which  may  happen 
in  running  a locomotive  ? 

Answer.  The  most  serious  accidents  are  : 

1.  Collision  of  two  trains  approaching  each  other. 

2.  Collision  of  a moving  with  a standing  train. 

3.  Collision  of  trains  at  the  crossing  of  two  railroads. 

4.  Running  a train  into  the  opening  left  by  an  open  draw-bridge. 

5.  Escape  of  an  engine  without  any  one  on  it. 

6.  Running  off  the  track. 

7.  Explosion  of  the  boiler. 

8.  Bursting  or  rather  collapse  of  a flue. 

9.  Overheating  and  burning  of  the  crown-sheet. 

10.  Blowing  out  of  a bolt,  stud,  rivet,  cock,  or  any  accident  which 
makes  or  leaves  a hole  in  the  boiler  for  the  escape  of  steam  or  water. 

11.  Failure  of  the  feed-pumps,  injector,  or  check-valve. 

12.  Breaking  or  bursting  of  a cylinder,  cylinder-head,  steam-chest, 
or  steam-pipe. 

13.  Breaking  or  getting  loose  of  the  piston  or  cross-head,  or  bending 
of  the  piston-rod. 

14.  Breaking  or  bending  of  a connecting-rod  or  crank-pin. 

15.  Breaking  of  a tire,  wheel,  or  axle. 

16.  Breaking  of  a spring,  spring-hanger  or  equalizer. 

17.  Breaking  of  a frame. 

18.  Breaking  or  getting  loose  of  a part  of  the  valve-gear. 

19.  Failure  of  the  throttle- valve. 

20.  Breaking  of  the  smoke-box  front  or  door. 

21.  Breaking  of  a coupling  between  the  engine  and  tender,  or  between 
the  tender  and  front  part  of  train,  or  between  two  cars. 

22.  Failure  of  the  air-pump  or  other  part  of  the  brake. 

QUESTION  854.  What  should  be  done  to  prevent  a collision  when  two 
trains  are  approaching  each  other  ? 


644 


Catechism  of  the  Locomotive. 


Answer.  The  obvious  thing  to  do  is  to  stop  the  trains  as  soon  as  pos- 
sible. This  is  done  by  applying  the  brakes  at  once  with  all  their  power, 
and  then  reversing  the  engine,  although  it  is  best  not  to  do  the  latter 
until  the  train  is  somewhat  checked,  as  there  is  always  danger  of  bursting 
the  cylinder  or  breaking  the  cylinder-heads,  piston,  or  connections  if  an 
engine  is  reversed  suddenly  at  a high  speed.  Of  course  the  higher  the 
speed,  the  greater  is  the  danger  of  injury  from  this  cause,  and  therefore 
it  is  best  if  there  is  time,  first  to  check  the  speed  of  the  train  before  revers- 
ing the  engine.  When  the  engine  is  reversed,  the  sand-valves  should  be 
opened  so  as  to  increase  the  adhesion  of  the  wheels,  so  that  when  their 
motion  is  reversed  they  may  check  the  speed  of  the  train  as  soon  as  pos- 
sible. On  perceiving  danger  ahead  the  order  of  procedure  should  be  as 
follows  : 

1.  Shut  the  throttle-valve. 

2.  If  the  train  is  equipped  with  hand-brakes  alone,  blow  the  danger 
signal  for  their  application,  or  if  the  train  has  a continuous  brake,  apply 
it  with  its  full  force. 

3.  Reverse  the  engine  and  open  the  throttle  and  the  sand-valves. 

4.  If  a collision  is  inevitable,  shut  the  throttle-valve  before  the  engines 
meet,  because  if  it  is  left  open  after  the  collision,  and  when  the  speed  of 
the  train  is  checked,  the  engine,  if  not  disabled  will  by  its  own  power 
crush  through  the  wreck,  and  thus  do  additional  damage. 

To  the  credit  of  locomotive  engineers,  it  can  be  said  that  they  rarely 
leave  their  engines,  no  matter  how  imminent  the  danger  is,  until  after 
they  have  applied  all  the  means  of  checking  the  speed  of  the  train.  If  a 
violent  and  dangerous  collision  is  inevitable,  then  the  engineer  may  pro- 
tect himself  by  jumping  from  his  engine,  or  remain  on  it  as  may  seem 
best ; but  he  is  in  duty  bound  to  do  all  in  his  power  to  prevent  dangerous 
collisions,  especially  if  he  is  running  a passenger  train. 

Question  855.  What  kind,  of  collisions  occur  oftenest  ? 

Answer.  What  are  called  ‘ tail-end  collisions” — that  is,  collisions 
of  trains  which  run  in  the  same  direction,  although  there  are  unfortu- 
nately many  collisions  of  trains  running  in  opposite  directions,  or  “butt- 
ing collisions,”  as  they  are  called. 

QUESTION  856.  What  should  be  done  if  another  train  is  approaching  a 
standing  train , arid  there  is  danger  of  a collision  ? 

Answer.  The  locomotive  runner  of  the  standing  train  should  start  his 
engine  in  the  same  direction  as  the  approaching  train  is  running  as 
quickly  as  possible,  because  the  shock  of  the  collision  will  be  very  much 


Accidents  to  Locomotives. 


645 


lessened  if  both  trains  are  moving  in  the  same  direction  compared  with 
what  it  would  be  if  one  was  standing  still. 

Question  857.  What  should  be  done  to  avoid  a collision  at  a railroad 
crossing  ? 

Answer.  If  there  are  no  interlocking  and  distant  signals  at  the  cross- 
ing, trains  should  always  come  to  a dead  stop  before  crossing  another 
railroad  on  the  same  level. 

If  there  are  interlocking  and  distant  signals,  the  engineer  should  be 
absolutely  sure  that  they  indicate  to  him  that  the  crossing  is  clear.  If 
by  reason  of  fog  or  inadvertance  in  looking  for  the  signals  or  any  other 
reason  he  has  the  slightest  doubt  about  the  position  of  the  distant  signal, 
he  should  slack  up  when  he  passes  it  so  as  to  be  able  to  stop  before  he 
reaches  the  home  signal  at  the  crossing.  If,  however,  through  any  cause 
danger  of  a collision  should  be  incurred  at  a crossing,  then  evidently  the 
one  train  should  be  stopped  and  the  other  moved  out  of  the  way  as  soon 
as  possible.  The  following  is  a safe  rule  for  all  persons,  as  well  as  locomo- 
tive engineers  to  adopt:  Never  cross  a railroad  without  first 
STOPPING  TO  SEE  WHETHER  THE  ROAD  IS  CLEAR.  If  those  who  drive 
horses  as  well  as  those  who  drive  locomotives,  and  also  foot  travelers, 
would  scrupulously  observe  this  rule,  many  lives  and  much  suffering  would 
be  saved  each  year. 

QUESTION  858.  How  can  an  accident  by  running  into  the  opening  at  a 
drawbridge  be  avoided? 

Answer.  The  precautions  to  be  taken  are  very  much  the  same  as  those 
which  should  be  observed  at  crossings.  It  is  a safe  rule  always  to  come 
to  a dead  stop  before  reaching  a drawbridge,  and  second,  never  start 
again  until  it  is  absolutely  certain  that  the  draw  is  closed.  Of  course  if  a 
locomotive  runner  of  an  approaching  train  finds  a draw  open,  the  only 
thing  he  can  do  is  to  stop  as  soon  as  possible. 

Question  859.  What  measures  should  be  taken  to  prevent  locomotives 
from  escaping  and  running  away  without  a responsible  person  on  them  ? 

Answer.  In  the  first  place,  when  a locomotive  is  left  standing,  the 
throttle-valve  should  always  be  closed  and  fastened ; the  cylinder-cocks 
should  also  be  opened,  so  that  if  any  steam  leaks  into  the  cylinders  it  will 
not  accumulate  there,  but  will  escape,  and  the  reverse  lever  should  be 
placed  in  the  centre  of  the  sector,  so  that  if  by  any  accident  the  throttle 
should  be  opened  the  engine  will  not  start. 

QUESTION  860.  If  a locomotive  should  escape , what  should  be  done,  and 
how  may  it  be  captured? 


G4G 


Catechism  of  the  Locomotive. 


Answer.  The  first  thing  to  be  done  is  to  telegraph  to  the  stations 
toward  which  the  escaping  engine  is  running,  either  to  keep  the  track 
clear,  or  if  there  is  a train  approaching,  to  open  a switch,  and  thus  let  the 
engine  run  off  the  track.  An  escaped  engine  may  be  captured  by  a 
swifter  engine  following  it,  but  this  is  always  attended  with  great  danger, 
as  the  first  engine  may  leave  the  track  or  become  wrecked.  A safer  plan 
is  to  telegraph  ahead  of  the  escaping  engine,  and  have  an  engine  placed 
in  a position  where  the  track  can  be  seen  for  a long  distance  in  the 
direction  in  which  the  runaway  is  expected.  As  soon  as  the  latter  comes 
in  sight,  the  waiting  engine  should  start  in  the  same  direction,  so  that 
when  they  get  near  to  each  other  they  will  both  be  running  the  same  way 
and  at  nearly  the  same  speed.  By  regulating  the  speed  of  the  front 
engine,  the  following  one  may  be  allowed  to  come  up  to  it  quite  gently, 
and  then  a man  can  easily  climb  from  the  one  engine  to  the  other,  and 
thus  both  be  stopped. 

QUESTION  861.  What  should  be  done  in  case  an  engine  gets  off  the 
track ? 

Answer.  The  first  thing  to  do  is  to  close  the  throttle-valve  and  “ signal 
for  brakes,”*  or  apply  the  continuous  brakes  if  the  train  is  equipped  with 
them,  and  then  reverse  the  engine.  As  soon  as  the  engine  has  stopped 
it  should  be  seen  that  the  proper  signals  are  given  to  protect  it  from 
approaching  or  following  trains.  If  the  boiler  is  in  such  a position  that 
the  heating  surfaces  are  liable  to  be  uncovered  with  water,  they  may  get 
red  hot  and  be  burned.  If  there  is  danger  of  this  the  fire  should  be  either 
drawn,  quenched  with  water,  or  extinguished  by  covering  it  with  sand, 
gravel,  earth,  sod,  or  snow,  and  then  wetting  the  covering. 

Question  862.  How  is  a locomotive  replaced  on  the  track  in  case  it  gets 
off ? 

Answer.  If  the  engine  is  still  standing  on  its  own  wheels,  and  has  not 
gone  far  from  the  rails,  it  can  usually  run  itself  back  by  the  aid  of  hydraulic 
jacks,  wrecking  frogs,  or  blocking  under  the  wheels.  Generally  it  can  be 
replaced  on  the  track  best  by  running  it  the  reverse  direction  to  that  in 
which  it  ran  off.  Often  a derailed  engine  can  be  put  back  with  the  aid  of 
another  engine  when  it  could  not  run  itself  back.  It  is  impossible  to  give 
any  directions  for  replacing  locomotives  on  the  track  which  will  meet  the 
great  variety  of  circumstances  which  occur  in  practice.  If  an  engine  has 
fallen  on  its  side  or  has  run  down  an  embankment,  it  is  usually  necessary 

* This  expression  means,  among  railroad  men,  to  signal  to  brakemen  by  blowing  the  whistle 
to  apply  the  brakes. 


Accidents  to  Locomotives. 


G47 


to  send  for  the  appliances  which  are  now  provided  on  nearly  all  roads  for 
removing  wrecks  and  replacing  engines  on  the  track.  These  appliances 
are  generally  stored  in  what  is  called  a wrecking  or  tool  car,  which  is 
placed  at  a convenient  point  on  the  road,  from  which  it  can  be  sent  to 
any  place  where  its  services  are  likely  to  be  needed.  Such  cars  are  pro- 
vided with  ropes,  jack-screws,  chains,  crowbars,  levers,  etc.,  to  be  used  in 
such  cases,  and  generally  a special  set  of  men  is  sent  with  the  wrecking 
car  to  direct  and  assist  in  replacing  engines  and  cars  on  the  track.  It 
would  lead  us  too  far  to  describe  all  the  methods  of  doing  this  employed 
under  various  circumstances  ; and  as  such  work  seldom  forms  part  of  the 
duties  of  a locomotive  runner,  a complete  description  would  be  out  of 
place  here. 

QUESTION  863.  After  an  accident  which  disables  the  engine , what  is 
the  first  thing  to  do  ? 

Answer.  The  first  thing  to  do  is  always  to  PROTECT  the  train,  that 
is,  to  send  out  signal  men  in  each  direction  to  stop  approaching  trains, 
otherwise  they  might  run  into  the  wrecked  train,  and  thus  cause  a double 
accident. 

QUESTION  864.  What  is  the  chief  cause  of  boiler  explosions? 

Answer.  The  cause  of  all  boiler  explosions,  as  happily  expressed  by  a 
prominent  American  engineer,*  is  that  the  pressure  inside  the 
BOILER  IS  GREATER  THAN  THE  STRENGTH  OF  THE  MATERIAL  OUTSIDE 
TO  RESIST  that  PRESSURE.”  This  may  occur  in  two  ways : first,  and 
most  frequently  with  locomotives,  from  insufficient  strength  of  the  boiler 
to  bear  the  ordinary  working  pressure ; and  second,  from  the  gradual 
increase  of  heat  and  pressure  until  the  latter  is  greater  than  the  boiler 
was  calculated  to  bear. 

Insufficient  strength  may  be  due : 1,  to  defects  of  the  original  design, 
owing  to  the  ignorance  of  the  strains  to  which  the  material  of  the  boiler 
will  be  exposed,  and  its  power  of  resistance ; 2,  to  defective  workmanship 
and  material,  which  can  usually  be  discovered  by  careful  inspection  ; 3,  to 
the  reduction  of  the  original  strength  of  the  boiler  by  corrosion  or  other 
ordinary  wear  and  tear  or  neglect,  which  can  also  usually  be  discovered 
by  careful  inspection. 

The  first  two  causes  have  been  fully  discussed  in  the  part  relating  to 
Boiler  Construction,  and  the  last  under  the  head  of  Inspection  of  Loco- 
motives. 

* Coleman  Sellers.  See  Fifth  Annual  Report  of  the  American  Master  Mechanics’  Associa- 
tion, page  196. 


648 


Catechtsm  of  the  Locomotive. 

Over-pressure  is  nearly  always  due  to  some  defect  of  the  safety-valve, 
or  to  the  fact  that  it  is  overloaded.  This  latter  often  occurs  when  safety- 
valves  are  set  by  an  incorrect  steam'-gauge,  which  indicates  too  little  press- 
ure. Over-pressure  may  afe^pcO\irtby  letting  an  engine  stand  alone  with 
a large  fire  in  its  fire-bo^  and  possibly  with  the  hlower,turned  on. 

A boiler  may,  IwvSikidenly  opening  the^hrottle-vatve,  undoubtedly  be 
subjected  to  vpsylevere  strain  that  m^ay^possibly  be  sufficient  to  cause  its 
destruction,  even  though  it  had  sufficient  ^trefigth  to  bear  the  ordinary 
pressure  at  which  the  safetyr valve  blowstoff.  Suddenly  opening  or  closing 
the  throttle-valve  may  produced  violent  rash  of  steam  and  water  against 
the  part  of  the  boiler  whence |h^steam  is  drawn.  The  percussion  of  the 
water  and  steam  in  such  ^ases^has  been  known  to  shake  the  whole  boiler, 
and  to  lift  the  safety-valve  momentarily  right  off  its  seat.*  The  weakest 
parts  of  a locomotive  are  the  two  sides  where  the  barrel  joins  the  outside 
fire-box.  Many  boilers,  especially  those  with  a high  wagon-top,  have  flat 
spaces  at  this  point,  which  it  is  impossible  to  stay  properly.  It  is  at  this 
point,  too,  that  the  expansion  and  contraction  of  the  tubes  and  the  outside 
shell  exert  their  greatest  strains,  and  it  will  therefore  be  found,  generally, 
that  the  seams  at  this  point  begin  to  leak  before  any  others,  and  for  these 
reasons  it  is  believed  that  all  the  seams  which  join  the  outside  shell  of  the 
fire-box  to  the  barrel  should  be  double-riveted. 

The  practice  of  ascribing  steam-boiler  explosions  to  obscure  causes  has 
been  productive  of  much  mischief,  as  it  engenders  a carelessness  on  the 
part  of  those  having  charge  of  them,  who  have  been  led  to  believe  that 
no  amount  of  care  will  avail  against  the  mysterious  agents  at  work  within 
the  boiler.  Explosions  are  also,  in  the  absence  of  other  convenient 
reasons,  very  generally  attributed  to  shortness  of  water.  This  is  often 
nothing  more  than  a convenient  method  of  shifting  the  responsibility 
from  the  builder  or  owner  of  the  locomotive  to  the  engineer  or  fireman, 
who,  if  not  killed  by  the  explosion,  in  many  cases  might  almost  as  well  be, 
so  far  as  his  ability  to  defend  himself  is  concerned.! 

Question  865.  What  should  a locomotive  engineer  and  fireman  do  to 
avoid  and  prevent  explosions  ? 

Answer.  1.  The  height  of  the  water  in  the  boiler  should  always  be 
maintained  so  as  to  cover  the  heating  surfaces.  2.  The  boiler  should  be 
kept  as  clean — that  is,  as  free  from  scale,  mud,  and  other  impurities,  as 
possible.  3.  It  should  never  be  subjected  to  strains  from  sudden  heating 

* Wilson  on  Boiler  Construction, 
t Ibid. 


Accidents  to  Locomotives. 


640 


or  cooling.  4.  The  steam-gauge  and  safety-valves  should  be  examined 
and  tested  frequently,  to  be  sure  they  are  in  order ; and,  5,  they  should 
examine  every  part  of  the  boiler  which  is  accessible,  but  especially  the 
stay-bolts,  to  see  that  there  is  no  fracture  of  any  part  or  any  injurious 
corrosion  or  other  dangerous  defect. 

Question  866.  If  from  any  defect  of  the  safety-valve  or  other  cause  the 
steam  should  rise  beyond  the  limit  of  pressure  that  should  be  carried,  what 
should  a?i  engineer  do  ? 

Answer.  He  should  open  the  furnace-door  and  heater-cocks,  and  let 
the  steam  blow  into  the  tank,  start  the  injector,  and  if  the  case  is  critical 
blow  the  whistle,  which  will  allow  some  of  the  steam  to  escape. 

Question  867.  What  should  be  done  in  case  of  the  bursting  or  collapse 
of  a tube? 

Answer.  As  soon  as  possible  after  it  occurs,  the  engineer  must  stop  the 
train  and  reduce  the  steam  pressure.  The  water  escaping  from  the  flue 
will  usually  quench  the  fire.  When  the  steam  pressure  is  reduced  the 
engineer  should  close,  first,  the  end  of  the  flue  in  the  fire-box,  and  then 
that  in  the  smoke-box,  by  driving  in  iron  plugs,  which  are  usually  provided 
for  the  purpose.  These  plugs  are  attached  to  the  end  of  a bar,  with  which 
they  are  inserted  into  the  tubes.  If  the  escape  of  water  and  steam  from 
the  tube  is  so  great  as  to  make  it  difficult  to  see  the  end  of  the  tube,  the 
steam  may  sometimes  be  drawn  up  the  chimney  by  starting  the  blower. 
If,  however,  the  escape  is  so  great  as  to  make  it  impossible  to  insert  the 
plug,  then  the  steam  pressure  must  be  reduced  by  running  with  both 
pumps  on,  or  by  starting  the  injector  ; or  it  may  be  necessary  to  smother 
or  draw  the  fire  and  cool  off  the  engine.  When  a flue  collapses,  the  front 
end  of  which  is  behind  the  steam  or  petticoat  pipes,  it  is  usually  necessary 
to  cool  off  the  engine  before  a plug  can  be  inserted,  especially  if  any  con- 
siderable amount  of  water  and  steam  escape  from  it.  While  driving  in 
the  plug,  the  engineer  and  fireman  should  always  keep  themselves  in  such 
positions  that  the  plug  cannot  hit  them  in  case  it  is  blown  out  by  the 
steam.  If  the  engine  is  not  supplied  with  iron  flue-plugs,  a wooden  plug 
can  be  cut  of  the  proper  size  and  driven  in.  This  can  be  attached  to  the 
bar  referred  to  and  inserted  ; but  if  no  such  bar  is  carried  with  the  engine, 
the  wooden  plug  can  be  made  on  the  end  of  a long  pole  and  then  cut 
nearly  off.  It  is  then  inserted  into  the  flue  and  driven  in  and  broken  off. 
It  will  be  found  that  such  plugs  will  burn  off  even  with  the  end  of  the  flue, 
but  will  not  burn  entirely  out. 

QUESTION  868.  What  should  be  done  in  case  a bolt,  stud,  rivet, 


650 


Catechism  of  the  Locomotive. 


or  cock  blows  out  of  the  boiler  and  thus  allows  the  steam  or  hot  waief 
to  escape? 

Answer.  If  the  opening  is  accessible,  cut  a plug  on  the  end  of  a long 
pole  and  drive  it  into  the  hole  in  the  same  way  as  described  above. 
This  will  avoid  the  necessity  of  cooling  off  the  engine  ; but  in  some  cases 
it  will  be  found  that  a plug  cannot  be  inserted  or  driven  in  without  draw- 
ing the  fire  and  cooling  off  the  boiler. 

Question  869.  In  case  it  is  found  necessary  to  draw  the  fire  and  cool 
off  the  boiler , and  if  so  much  water  has  escaped  as  to  uncover  the  crown- 
plate,  what  must  be  done? 

Answer.  If  the  leak  has  been  stopped  or  the  fault  remedied,  one  of  the 
safety-valves  should  be  taken  off  and  water  poured  into  the  boiler  with 
pails  or  buckets  through  the  opening  left  by  the  removal  of  the  safety- 
valve  until  the  crown-sheet  is  covered.  The  fire  may  then  be  kindled 
again  and  the  engine  complete  its  journey.  When  bituminous  coal  is 
used  for  fuel,  the  necessity  for  drawing  the  fire  in  case  of  accident  may 
often  be  avoided  by  completely  covering  or  “ banking  ” the  fire  with  fine 
coal  which  has  been  wet,  and  closing  the  dampers  and  opening  the  fur- 
nace door.  In  this  way  the  fire  may  be  smothered  and  the  boiler  cooled 
without  putting  the  fire  out,  so  that  after  the  defect  is  remedied  it  will 
not  be  necessary  to  rekindle  it. 

Question  870.  What  must  be  done  in  the  case  of  the  failure  of  one  or 
both  the  injectors,  feed-pumps,  or  check-valves? 

Answer.  If  one  of  the  injectors  or  pumps  fails  the  other  one  may  be 
used,  but  the  defect  or  obstruction  to  the  first  should  be  remedied  as  soon 
as  possible,  because  the  second  may  also  fail.  A description  of  the  most 
common  defects  of  injectors  will  be  found  in  answer  to  Questions  811,  812 
and  818. 

Question  871.  In  case  a pump  fails,  how  should  it  be  examined  in 
order  to  discover  the  defect  ? 

Answer.  It  should  first  be  seen  whether  there  is  plenty  of  water  in  the 
tank,  and  whether  the  strainer  is  obstructed  or  not.  The  working  of  a 
pump  is  usually  indicated  by  the  stream  which  escapes  from  the  pet-cock. 
If,  when  this  is  opened,  steam  and  water  escape,  it  is  an  indication  that 
the  check-valve  is  not  working  properly.  If  it  is  not  working  well  hot 
water  will  escape  if  the  pet-cock  is  opened  when  the  engine  is  standing 
still,  but  the  pump  may  still  feed  the  boiler  if  the  upper  or  pressure-valve 
works  properly.  When  the  check-valve  does  not  work  as  it  should,  it  is 
also  indicated  by  the  heating  of  the  feed-pipe,  owing  to  the  escape  of  hot 


Accidents  to  Locomotives. 


651 


water  from  the  boiler  through  the  check-valve  when  the  pet-cock  is 
opened.  If,  when  the  plunger  is  drawn  out  of  the  pump,  air  is  sucked  in 
through  the  open  pet-cock,  then  the  upper  or  pressure-valve  of  the  pump 
does  not  work,  but  the  working  of  the  pump  may  still  be  secured  by  the 
working  of  the  check-valve ; but  if  the  pump,  air-chamber,  and  feed-pipe 
then  get  filled  with  air,  the  plunger  may  compress  this  air  at  each  stroke, 
and  as  it  can  then  follow  the  plunger  during  its  outward  stroke,  the  latter 
will  not  suck  water,  but  will  simply  compress  the  air  during  the  inward 
stroke,  which  will  then  expand  during  the  outward  stroke.  This  will  be 
indicated  by  the  escape  of  air  from  the  pet-cock  when  the  plunger  is  mov- 
ing inward,  and  the  suction  of  air  when  the  plunger  is  moving  outward. 
This  can  be  known  by  holding  the  hand  in  front  of  the  pet-cock.  Usually, 
however,  the  air  is  mixed  with  water,  so  that  the  stream  which  escapes 
from  the  pet-cock  is  broken  or  irregular.  If  air  escapes  from  the  pet- 
cock  during  the  inward  stroke  of  the  plunger,  but  none  is  sucked  in  dur- 
ing the  outward  stroke,  it  shows  that  there  is  a leak  somewhere  in  the 
pump  or  pipes,  and  that  it  is  pumping  air  instead  of  water.  The  leak 
may  be  in  the  stuffing-box  of  the  plunger,  the  joints  of  the  pump  or  pipes, 
in  the  hose  or  their  connections  with  the  supply-pipe  or  tender.  If  neither 
air  nor  water  escapes  from  the  pet-cock  during  the  inward  stroke  of  the 
pump-plunger,  or  if  the  stream  of  water  at  that  time  is  weak,  then  it  indi- 
cates that  the  suction  or  lower  valve  of  the  pump  is  not  working  properly. 
The  same  thing  will  occur  if  the  pipe,  pump,  or  tender-valve  is  obstructed. 
If  there  is  a cock,  as  there  always  should  be,  just  above  the  suction-valve, 
it  will  aid  very  much  in  discovering  the  fault  when  the  pump  will  not 
work.  If,  when  this  cock  is  opened,  cold  water  escapes  from  it,  the  fault 
is  in  the  suction-valve ; if  hot  water,  then  it  is  the  pressure  and  check- 
valves  which  are  leaky,  obstructed,  or  broken,  and  consequently  the  hot 
water  from  the  boiler  leaks  back  into  the  pump.  In  the  absence  of  such 
a cock,  the  fault  can  often  be  discovered  by  feeling  the  pump  barrel  with 
the  hand.  If  the  pump  cannot  be  made  to  work,  and  the  fault  is  found 
to  be  in  the  lower  valve,  it  must  be  taken  out  and  examined  ; or  if  the 
fault  is  in  the  pipes,  it  can  usually  be  easily  remedied.  If  the  pipes  are 
burst  with  only  a small  fracture,  it  can  usually  be  repaired  temporarily  by 
covering  the  aperature  with  canvas  or  india  rubber  and  wrapping  twine 
around  it  tightly.  The  upper  valve  of  a pump  must,  however,  never  be 
taken  down  without  first  being  sure  that  the  check-valve  is  tight,  because  if  it 
is  not,  the  person  will  be  likely  to  be  scalded  in  taking  the  pump  apart. 

Only  after  all  the  appliances  for  feeding  the  boiler  have  failed  and  the 


652 


Catechism  of  the  Locomotive. 


water  is  so  low  as  to  be  in  danger  of  exposing  the  crown-sheet,  should  the 
fire  be  drawn  or  banked,  and  the  engineer  should  then  at  once  give  the 
proper  signals  for  warning  and  the  protection  of  his  train,  and  if  he  is 
unable  to  repair  the  pumps  or  injector,  he  must  send  for  aid  to  the  nearest 
accessible  point. 

Directions  for  taking  care  of  pumps  in  cold  weather  have  already  been 
given  in  the  answers  to  Question  292. 

Question  872.  What  are  the  principal  causes  of  broken  cylinders  and 
cylinder -heads  ? 

Answer.  Such  accidents  are  usually  caused  by  collisions,  water  in  the 
cylinders,  broken  cross-heads,  piston-rods,  main  connecting-rods,  crank- 
pins,  or  pistons. 

Question  873.  What  is  often  the  origin  of  such  accidents? 

Answer.  They  are  often  due  to  neglect  in  opening  the  cylinder-cocks, 
taking  up  lost  motion  in  boxes,  keys,  or  bolts.  Lost  motion  of  the 
brass  bearings  of  the  main  connecting-rod,  or  a loose  key  in  the  piston- 
rod,  or  loose  bolt  in  the  follower-plate  cause  an  undue  strain  on  the  con- 
nected parts  which  eventually  results  in  a breakage.  The  same  thing 
occurs  when  such  parts  as  the  piston-rods,  guides,  or  pump-plungers  are 
out  of  line. 

Question  874.  What  should  be  done  in  case  of  the  breaking  or  burst- 
ing  of  a cylinder  or  cylmder-head? 

Answer.  If  the  guides,  cross-head,  main  connecting-rod  and  crank- 
pin  are  uninjured  they  need  not  be  removed,  but  the  piston-rod  may  be 
disconnected  from  the  cross-head,  and  the  piston  should  be  taken  out  of 
the  cylinder.  If  any  of  the  above  parts  are  injured  so  that  they  will  not 
work,  then  the  main  connecting-rod  must  be  taken  down  on  that  side  of 
the  engine.  In  doing  this  care  should  be  taken  to  put  back,  in  their 
proper  places,  all  liners — if  there  are  any — in  the  straps.  This  will  save 
some  trouble  in  replacing  the  rods.  The  piston  should  then  be  moved  to 
the  front  or  back  end  of  the  cylinder  and  wooden  blocks  be  placed 
between  the  guides  so  as  to  fill  up  the  space  between  the  cross-head  and 
the  end  of  the  guide-bars,  and  thus  prevent  the  cross-head  and  piston 
from  moving.  If  a single  guide  is  used,  blocks  can  be  put  above  and 
below  the  cross-head,  and  bolted  or  tied  with  rope  in  their  places.  It  is 
usually  best  to  block  the  piston  at  the  extreme  back  end  of  the  cylinder, 
because  in  that  position,  if  it  should  get  loose  and  be  driven  to  the  front 
end,  less  damage  would  be  done  than  would  follow  if  the  piston  was  at 
the  front  end  and  was  driven  backward  so  as  to  injure  the  back-head. 


Accidents  to  Locomotives. 


653 


guides,  etc.  On  some  engines,  such  as  moguls  and  consolidations,  the 
piston  must  be  placed  in  the  front  end  of  the  cylinder  when  the  cross- 
head is  blocked,  because  the  crank-pin  of  the  front  driving-wheel  may  not 
clear  the  cross-head  if  the  lattel*  is  at  the  back  end  of  the  guides.  When 
the  cross-head  is  blocked  the  valve  stem  should  be  disconnected  from  the 
rocker,  and  the  valve  moved  to  the  middle  of  the  valve  face,  so  as  to 
cover  up  both  steam-ports  and  prevent  steam  from  entering  the  cylinders 
and  moving  the  piston.  It  can  be  known  whether  the  valve  is  in  the 
middle  of  the  valve  face  by  admitting  a little  steam  to  the  steam-chest 
and  opening  the  cylinder-cocks.  If  it  is  not  in  the  middle  of  the  face  so 
as  to  cover  both  ports,  steam  will  escape  at  the  end  of  the  cylinder  whose 
port  is  uncovered.  When  the  valve  is  in  the  middle  of  the  face  no  steam 
— excepting  that  due  to  the  leakage  of  the  valve — will  escape  at  either 
end.  It  must  then  be  fastened  in  that  position  by  screwing  up  one  of  the 
bolts  of  the  stuffing-box  of  the  valve  stem,  so  as  to  make  the  gland  bind 
against  the  valve  stem.  When  metallic  packing  is  used  the  valve  stem 
must  be  wedged  or  tied  in  its  place. 

If  both  front  cylinder-heads  are  broken  and  the  working  parts  of  the 
engine  are  uninjured  the  steam-chest  cover  should  be  taken  off,  and  the 
front  steam-ports  filled  with  wood.  The  engine  can  then  be  run  with  a 
light  train,  by  admitting  steam  into  the  front  ends  only  of  the  cylinders. 

If  one  or  both  of  the  cylinders  arj  disabled  the  train  should  be  run 
cautiously  to  the  next  station.  If  the  engine  is  not  able  to  haul  the  train, 
then  it  should  be  uncoupled  and  run  to  the  first  telegraph  station  or  other 
point  where  the  aid  of  a helping  engine  can  be  obtained  or  telegraphed 
for.  In  the  mean  while,  the  train  must  be  protected  by  the  proper  signals. 
Should  the  engine  continue  its  journey,  it  must  be  started,  if  it  should 
happen  to  be  standing  at  the  dead-point,  by  pushing  or  by  means  of  crow- 
bars. In  so  doing,  however,  the  bars  should  not  be  put  between  the 
spokes  of  the  wheels,  as  they  may  easily  be  caught  in  the  wheels  when  the 
engine  starts,  and  in  this  way  the  spokes  be  broken  or  the  persons 
using  the  crow-bars  be  badly  hurt.  If  it  is  necessary  to  disconnect  the 
engine,  in  freezing  weather,  then  all  pipes,  pumps,  and  injectors  liable  to 
freeze  must  be  drained.  If  there  are  no  cocks  or  plugs  for  this  purpose, 
then  the  connections  should  be  slacked  up  so  as  to  allow  the  water  to  run 
out,  and  when  it  is  possible  to  do  so  blow  steam  through  the  pipes  to 
clear  them  of  water. 

Question  875.  In  case  an  engine  must  be  towed,  what  must  always  be 
done  % 


654 


Catechism  of  the  Locomotive. 


Answer'.  The  main  rods  and  the  valve  stems  must  always  be  discon- 
nected, for  the  reason  that  it  is  impossible,  or  very  difficult  to  keep  the 
pistons  and  valves  properly  lubricated  without  steam  on  the  engine,  and, 
therefore,  if  they  were  in  motion  when  the  engine  was  running  without 
steam,  they  are  liable  to  cut  the  cylinder  and  valve-seats.  If  there  is 
danger  of  the  water  in  the  boiler  and  in  the  tank  freezing,  they  should 
both  be  emptied. 

QUESTION  876.  What  must  be  done  in  case  a steam-chest  or  steam-pipe 
is  broken  ? 

Ans7ver.  The  main  rod  and  valve-stem  on  that  side  must  be  discon- 
nected, as  already  explained.  If  a steam-chest  is  broken  a block  of  wood 
should  be  bolted  over  the  mouth  of  the  steam  passage,  so  as  to  prevent 
the  escape  of  the  steam  from  the  steam-pipe  on  that  side.  It  will  some- 
times require  considerable  ingenuity  to  devise  means  of  fastening  such  a 
block  or  blocks  of  wood  so  as  to  cover  the  mouth  of  the  steam  passage. 
As  cylinders  are  now  usually  made,  the  blocks  can  be  fastened  by  cutting 
them  to  the  proper  form  and  size,  and  then  placing  a thick  block  on  top, 
and  bolting  the  steam-chest  cover  down  on  top  of  it.  If  the  cover  is 
broken,  a part  of  it  may  be  used  or  a piece  of  plank  with  a few  holes 
bored  into  it,  or  fish-plates  may  be  employed  instead.  In  some  cases  a 
piece  of  board  can  be  bolted  over  the  end  of  the  steam-pipe.  When  the 
latter  is  broken,  it  should  be  taken  down  and  a piece  of  board  or  plank 
bolted  over  the  opening  of  the  T-pipe  to  which  the  steam-pipe  was 
attached.  Usually  it  is  difficult  to  take  down  a steam-pipe  in  the  smoke- 
box,  for  the  reason  that  the  bolts  and  nuts  are  rusted  fast  and  cannot  be 
unscrewed. 

Question  877.  What  must  be  done  if  a piston , cross-head , connecting- 
rod,  or  crank-pin  is  broken  or  bent  ? 

Answer.  If  the  piston,  cross-head,  or  main  connecting-rod,  or  main 
crank-pin  is  broken,  the  same  course  must  be  pursued  as  when  a cylinder  is 
broken.  If  a coupling-rod  or  a crank-pin  of  a trailing-wheel  of  an  engine 
with  four  coupled  wheels  is  broken,  then  it  is  necessary  to  take  down 
both  the  coupling-rods  but  not  to  disconnect  the  main  connecting-rods  or 
their  attachments,  unless  they  are  injured.  On  engines  with  six  or  eight 
wheels  coupled,  if  any  excepting  the  main  crank-pins  are  broken,  then  the 
only  coupling-rods  which  must  be  taken  down  are  those  connected  to  the 
pair  of  wheels  on  which  the  crank-pin  is  broken. 

QUESTION  878.  If  one  of  the  coupling-rods  connected  to  a pair  of  wheels  on 
one  side  is  taken  down , why  must  the  one  on  the  other  side  be  taken  down  also  ? 


Accidents  to  Locomotives. 


655 


Answer.  Because  if  only  one  rod  is  used  on  a pair  of  wheels  there  is 
then  nothing  to  help  the  cranks  of  those  wheels  past  the  dead-points,  so 
that  in  starting,  or  if  they  are  moving  slowly  when  they  reach  these  points, 
they  are  quite  as  likely  to  revolve  in  one  direction  as  the  other.  If  they 
happen  to  turn  in  the  reverse  direction  to  that  in  which  the  wheels  to 
which  they  are  coupled  are  moving,  then  the  crank-pins  of  one  or  the 
other  pair  of  wheels  are  very  liable  to  be  broken  or  bent. 

Question  879.  What  must  be  done  if  a driving-wheel  or  tire  breaks? 

Answer.  If  a tire  on  a main  driving-wheel  or  the  wheel  itself  breaks, 
the  broken  wheel  or  tire  should  be  held  up  clear  of  the  rails  by  putting  a 
wooden  block  under  the  driving-box.  If  the  crank-pin,  connecting-rods, 
etc.,  have  not  been  injured  it  is  not  essential  to  take  the  coupling-rods 
down.  If,  however,  it  is  necessary  to  disconnect  the  main  rods  on  both 
sides,  then,  of  course,  all  the  coupling-rods  must  be  taken  down.  If  both 
of  the  main  driving-wheels  have  been  disabled,  then  both  of  them  must 
be  blocked  up.  It  is  possible  but  not  probable,  that  both  tires  and 
even  part  of  both  wheels  might  be  broken,  leaving  the  crank-pins  and 
connecting-rods  intact.  In  that  event  by  blocking  up  the  boxes  it  would 
not  be  essential  to  disconnect  any  of  the  rods.  Usually,  however,  when 
both  of  the  main  driving-wheels  are  broken  both  sides  must  be  discon- 
nected and  the  engine  be  towed  in. 

If  a trailing  or  leading  driving-wheel  or  tire  is  broken  the  wheel  should 
be  blocked  up  and  the  coupling-rods  connected  to  the  pair  of  disabled 
wheels  must  be  taken  down.  When  both  trailing  wheels  or  axles  are 
broken  the  engine  can  sometimes  be  run  to  a side  track  by  supporting 
part  of  the  back  end  of  the  engine  on  the  tender.  This  can  be  done 
sometimes  by  chains  and  pieces  of  rails  or  timber,  attached  either  to  the 
engine  or  tender  frame.  An  ordinary  American  engine  can  then  be  run  on 
three  driving-wheels,  but  it  must  be  run  with  the  utmost  caution.  If  the  en- 
gine has  more  than  four  driving-wheels  there  is  usually  less  difficulty  in  run- 
ning it,  if  one  of  the  main  wheels  is  injured,  than  if  there  are  only  four. 

Question  880.  What  should  be  done  in  case  the  flange  of  a tire  or 
wheel  is  broken  ? 

Answer.  All  that  can  be  done  is  to  run  very  cautiously  and  slowly, 
especially  over  frogs  and  switches. 

Question  881.  What  should  be  done  in  case  a driving-axle  breaks? 

Answer.  If  a main  driving-axle  breaks  outside  of  one  of  the  boxes,  the 
wheel  next  to  the  break  should  be  removed,  the  box  blocked  up,  and  the 
engine  be  disconnected  on  that  side  and  all  the  coupling-rods  on  the  other 


656 


Catechism  of  the  Locomotive. 


side  be  taken  down.  The  engine  can  then  be  run  without  the  train  to  the 
nearest  telegraph  station.  If  the  main  axle  is  broken  between  the  boxes, 
all  that  can  be  done  is  to  disconnect  both  sides,  block  up  the  wheels  of 
the  broken  axle,  and  send  for  assistance. 

If  a leading  or  trailing  axle  breaks  the  coupling-rods  connected  thereto 
must  be  taken  down.  If  the  break  is  outside  the  boxes,  the  loose  wheel 
must  be  removed,  and  its  box  blocked  up.  If  the  break  is  between  the 
boxes,  both  wheels  must  be  blocked  up  and  the  engine  run  without  the 
train,  as  described  for  broken  wheels  or  tires. 

It  is  almost  impossible  to  give  directions  which  will  be  applicable  to  all 
the  accidents  of  this  kind  that  may  occur  to  different  kinds  of  engines. 
In  such  cases,  if  assistance  or  a telegraph  office  is  near  where  the  accident 
occurs,  it  is  usually  best  to  send  for  help  at  once,  rather  than  • take  the 
risks  which  attend  the  attempt  to  run  an  engine  so  seriously  injured. 

Question  882.  What  must  be  done  if  an  engine  truck-wheel  or  axle 
breaks ? 

Answer.  It  is  usually  best  to  chain  up  the  end  of  the  truck-frame  over 
the  broken  axle  or  wheel  to  the  engine-frame  and  place  a cross-tie  across 
the  other  end  of  the  truck-frame,  between  it  and  the  engine-frame,  so  that 
the  weight  of  the  engine  may  rest  on  the  cross-tie.  If  a part  of  the  flange 
or  a piece  of  the  wheel  is  broken  out,  the  wheels  should  be  turned  around 
so  that  the  unbroken  part  will  rest  on  the  rail,  and  they  should  then  be 
chained  or  otherwise  fastened  so  that  they  cannot  revolve,  and  thus  be 
made  to  slide  on  the  rails  and  carry  the  weight  of  the  engine  in  that  way. 
The  same  plan  is  employed  if  a tender  wheel  breaks,  but  one  end  of  a 
tender-truck  frame  must  be  chained  up.  It  is  usually  necessary  to  place 
a cross-tie  across  the  top  of  the  tender,  and  fasten  the  chains  to  it. 

Question  883.  What  must  be  done  in  case  a driving-spring , spring- 
hanger  or  equalizing-lever  breaks  ? 

Answer.  As  the  breaking  of  a spring  or  spring-hanger  may  cause  a 
more  serious  accident,  the  engine  and  train  should  be  stopped  as  soon  as 
possible  after  it  occurs.  If  the  hanger  is  broken  and* there  is  a duplicate 
on  hand,  it  should  be  substituted  in  place  of  the  broken  one.  If  there  is 
no  duplicate,  then  the  spring  should  be  taken  down,  and  a wooden  block 
be  placed  between  the  top  of  the  driving-box  and  the  frame,  to  support 
the  weight  which  before  rested  on  the  spring.  In  order  to  insert  this 
block,  if  it  is  a front  spring  which  is  broken,  it  is  usually  best  to  raise  the 
engine  with  jack-screws,  or  run  the  back  wheels  on  inclined  blocks  of 
wood  placed  under  each  of  the  back  wheels.  This  raises  the  weight  off 


Accidents  to  Locomotives. 


657 


from  the  front  wheels,  and  the  block  can  then  be  inserted  between  the 
box  and  frame.  If  it  is  one  of  the  springs  over  the  back  wheels  which  is 
broken,  the  front  wheels  should  be  run  on  the  wooden  wedges.  Such 
wedges  can  soon  be  cut  out  of  a cross-tie  with  an  axe,  or  by  sawing  a 
square  stick  of  wood  diagonally  it  will  make  two  such  wedges.  The  end 
of  the  equalizing-lever  next  to  the  broken  spring  must  be  supported  by 
inserting  a piece  of  wood  under  it.  This  will  usually  be  held  securely  by 
the  weight  which  is  suspended  from  the  opposite  end,  bearing  the  blocked 
end  down  on  the  block. 

In  case  a hanger  breaks  a chain  may  be  used  as  a temporary  substitute. 

QUESTION  884.  What  should  be  done  if  an  engine-truck  or  tender-spring 
breaks  ? 

Answer.  Very  much  the  same  course  must  be  pursued  that  is  employed 
when  a driving-spring  breaks,  excepting  that  usually  the  weight  can  be 
lifted  off  from  a truck-box  easier  by  placing  a jack  under  the  end  of  the 
truck-frame  than  by  the  method  described.  Usually,  too,  each  of  the 
truck-springs  supports  the  weight  on  t\yo  of  the  wheels,  so  that  the  two 
boxes  must  be  blocked  up. 

Question  885.  If  a truck  wheel  or  axle  breaks  or  an  axle  is  bentt  what 
should  be  done  ? 

Answer.  It  a back  wheel  of  a truck  is  broken,  it  can  be  chained  up, 
clear  of  the  track,  to  a cross-tie  on  top  of  the  engine-frame  or  on  top  of 
the  tank,  or  it  can  be  fastened  so  that  it  cannot  revolve  and  be  allowed  to 
slide  on  the  rails.  If  a front  wheel  or  axle  of  a four-wheeled  truck  is 
broken  or  bent,  the  engine  may  be  jacked  up  and  the  truck  turned  around 
so  as  to  bring  the  sound  pair  in  front. 

Question  886.  What  must  be  done  in  case  the  engine-frame  is  broken  ? 

Answer.  Usually  very  little  need  be  done  excepting  to  exercise  more 
than  usual  caution  in  running,  and  to  reduce  the  speed.  Of  course  the 
breakage  of  a frame  may  disable  the  engine,  but  ordinarily  in  such  acci- 
dents that  is  not  the  case. 

Question  887.  , How  can  it  be  known  if  an  eccentric  has  slipped  on  the 
axle  ? 

Answer.  It  is  indicated  at  once  by  the  irregular  sound  of  the  exhaust, 
or,  as  locomotive  runners  say,  the  engine  will  be  “ lame." 

Question  888.  When  it  is  known  that  a?i  eccentric  has  slipped , how 
can  it  be  learned  which  is  the  one  that  is  misplaced? 

Answer.  This  can  usually  be  learned  by  examining  the  marks  which 
should  always  be  made  on  the  eccentrics  and  on  the  axles.  If  no  such 


658 


Catechism  of  the  Locomotive. 


marks  have  been  made  by  the  builder  of  the  engine,  the  engineer  himself 
should  make  them,  after  the  valves  have  been  set  correctly.  The  effect 
upon  the  valve  when  an  eccentric  slips  is  either  to  increase  or  diminish 
the  lead.  Therefore,  by  running  the  engine  slowly  with  the  link  first  in 
full  forward  and  then  in  full  back  gear,  and  observing  whether  steam  is 
admitted  at  each  end  of  the  cylinder  just  before  the  crank  reaches  the 
dead  points,  it  can  be  known  which  eccentric  has  moved.  If  it  has  slipped 
in  one  direction  the  lead  will  be  increased  and  steam  will  be  admitted  to 
the  cylinder  some  time  before  the  piston  reaches  the  end  of  the  stroke. 
If  it  has  moved  the  opposite  way,  the  lead  will  be  diminished  and  steam 
will  not  be  admitted  until  after  the  piston  has  reached  the  end  of  its 
stroke.  The  admission  of  steam  will  be  indicated  by  its  escape  from  the 
cylinder-cocks. 

Question  889.  If  by  any  means  the  valve-stem  or  either  of  the  eccentric- 
rods  should  be  lengthened  or  shortened , how  can  it  be  known  ? 

Answer.  The  crank  on  one  side  should  be  placed  at  one  of  the  dead- 
points  and  the  cylinder-cocks  opened  ; then  admit  a little  steam  to  the 
cylinder,  by  opening  the  throttle-valve  slightly,  and  throw  the  reverse 
lever  from  full  gear  forward  to  full  gear  backward,  and  observe  whether 
steam  escapes  all  the  time  from  the  end  of  the  cylinder  at  which  the  piston 
stands.  Then  repeat  the  operation  with  the  crank  at  the  other  dead- 
point.  If  either  of  the  eccentric-rods  or  the  valve-stem  have  been  length- 
ened or  shortened,  it  will  cause  the  valve  to  cover  the  steam-port  either 
at  the  front  or  back  end  of  the  cylinder,  so  that  no  steam  will  escape  from 
the  cock  at  that  end.  If  the  length  of  one  of  the  eccentric-rods  has  been 
changed,  then  when  the  altered  rod  is  in  gear  the  valve  will  have  too  little 
or  no  lead  at  one  end  of  the  cylinder  and  too  much  at  the  other.  If, 
therefore,  this  occurs  when  the  forward  rod  is  in  gear  and  not  in  back 
gear,  it  indicates  that  the  length  of  the  forward  rod  has  been  altered.  If 
the  reverse  occurs  it  shows  that  it  is  the  back-motion  rod  whose  length 
has  been  changed.  It  must  be  observed  that  if  the  length  of  an  eccentric- 
rod  is  altered  the  lead  will  be  changed  only  at  that  part  of  the  link  which 
is  operated  by  the  altered  rod.  That  is,  if  the  forward  eccentric-rod  is  too 
long  or  too  short,  the  lead  at  the  front  and  back  ends  of  the  cylinder  in 
forward  gear  only  will  be  affected.  If  the  back  eccentric-rod  is  changed 
the  valve  will  be  affected  only  in  back  gear.  If,  however,  the  length  of 
the  valve-stem  is  changed,  the  lead  will  be  changed  in  both  forward  and 
back  gear.  The  valves  on  each  side  of  the  engine  can,  of  course,  be  tested 
in  the  same  way. 


Accidents  to  Locomotives. 


659 


QUESTION  890.  When  it  is  discovered  which  eccentric  has  slipped,  how 
should  it  be  reset  ? 

Answer.  If  it  has  been  marked,  it  is  simply  turned  back  so  that  the 
marks  correspond  with  each  other  again.  This  is  done  by  first  loosening 
the  set-screws,  and,  after  the  eccentric  is  turned  to  the  proper  place, 
tightening  them  up  again.  When  an  eccentric  slips  it  is  often  caused  by 
the  cutting  of  the  eccentric-straps,  valve  or  other  part  of  the  valve-gear, 
so  that  these  should  always  be  examined  to  see  whether  they  are  properly 
oiled.  If  the  eccentrics  have  not  been  marked,  the  valve  may  be  set  by 
placing  the  crank  at  the  forward  dead-point,  and  the  reverse  lever  in  the 
front  notch  of  the  sector  and  the  full  part  of  the  forward-motion*  eccentric 
above  the  axle.  Then  admit  a little  steam  into  the  steam-chest,  open  the 
cylinder-cocks,  and  move  the  forward-motion  eccentric  slowly  forward 
until  steam  escapes  from  the  front  cylinder-cock,  which  will  show  that 
the  steam-port  is  opened  and  the  valve  has  some  lead.  To  set  the  back- 
ward-motion eccentric  the  crank  is  placed  in  the  same  position,  but  the 
reverse  lever  is  thrown  into  the  back  notch  and  the  full  part  of  the  eccen- 
tric is  placed  below  the  axle.  Then  move  this  eccentric  forward  until 
steam  escapes  from  the  front  cylinder-cock  as  before.  In  order  to  verify 
the  position  of  the  eccentrics  the  crank  may  be  placed  at  the  back  dead- 
point  and  the  reverse  lever  moved  backward  and  forward,  at  the  same 
time  observing  whether  steam  escapes  from  the  back  cylinder-cock  when 
the  link  is  in  both  back  and  forward  gear. 

Question  891.  What  should  be  done  in  case  an  eccentric-strap  or  rod, 
or  rocker  arm,  rocker  shaft,  or  the  valve-stem  breaks  ? 

Answer.  If  an  eccentric-strap  or  rod  breaks,  the  broken  rod  and  strap 
should  be  taken  down,  and  the  valve-stem  disconnected  from  the  rocker 
and  the  valve  fastened  in  the  middle  position  of  the  valve-face,  and  the 
engine  should  be  disconnected  on  one  side  and  be  run  with  one  cylinder 
only.  The  same  course  must  usually  be  pursued  if  a rocker  breaks. 
If  the  valve-stem  breaks,  it  is  not  necessary  to  disconnect  the  link  and 
eccentric-rods,  but  simply  to  fasten  the  valve  in  the  centre  of  the  valve 
face. 

Question  892.  If  a link-hanger  or  saddle,  or  a lifting-arm  should 
break,  what  should  be  done? 

Answer.  The  valve-gear  may  be  used  on  that  side  of  the  engine  by 
putting  a wooden  block  in  the  link  slot  above  the  link  block,  so  as  to  sup- 
port the  link  near  the  position  at  which  it  works  the  valve  full  stroke  for- 
ward. Of  course  the  engine  can  then  be  run  in  only  one  direction,  and 


Catechism  of  the  Locomotive. 


660 

should  therefore  be  run  with  the  utmost  caution.  If,  however,  it  should 
be  necessary  to  back  the  train  on  a side  track,  it  can  be  done  by  taking 
out  the  wooden  block  and  substituting  a longer  one,  so  that  the  link  will 
be  supported  in  a position  near  that  at  which  it  works  the  valve  full  stroke 
backward.  These  blocks  must  be  fastened  in  some  way,  either  with  rope 
or  twine,  so  that  they  will  be  held  in  their  position  when  the  engine  is  at 
work. 

QUESTION  893.  If  the  lifting-shaft  itself  or  its  vertical  arm,  the  reverse 
lever  or  rod,  should  break,  what  can  be  done? 

Answer.  If  it  is  impossible  to  devise  any  temporary  substitute  or 
method  of  mending  them,  but  both  links  can  be  blocked  up  as  described 
above.  The  engineer  should  determine  as  near  as  he  can  the  point  of  cut- 
off at  which  the  engine  must  work  to  reach  its  destination.  For  forward 
motion  long  pieces  of  wood  would  be  placed  below  the  link-block  and 
short  ones  above.  To  back  the  engine  these  pieces  must  be  reversed. 
The  same  plan  can  be  used  if  one  or  both  of  the  lifting  shaft-arms,  the 
reversing-rod,  the  link-hanger,  or  the  hanger-pin  breaks. 

QUESTION  894.  If  a valve,  valve-yoke,  or  valve-stem  is  broken  inside 
of  the  steam-chest  how  can  it  be  known  and  located? 

Answer.  It  will  make  itself  known  by  the  irregular  exhaust  of  the 
Steam.  To  ascertain  on  which  side  the  defect  is,  one  of  the  crank-pins 
should  be  placed  at  a dead-point,  and  the  throttle-valve  and  cylinder- 
cocks  opened.  Then  move  the  reverse-lever  from  full  stroke  forward  to 
full  stroke  back.  In  doing  this,  if  the  valve  gear  is  in  good  condition,  the 
valve  will  have  good  lead  alternately  at  the  front  and  the  back  end,  and 
steam  will  escape  from  the  front  and  back  cylinder-cocks  as  the  reverse- 
lever  is  moved.  If  the  valve-stem  or  yoke  is  broken  the  valve  will  not  be 
moved  as  it  should  be  by  the  reverse-lever,  and  if  the  valve  is  broken, 
probably  it  will  be  indicated  by  the  irregular  or  constant  escape  of  steam. 
By  trying  both  sides  of  the  engine  the  defect  can  thus  be  located. 

Question  895.  If  the  valve,  valve-stem,  or  yoke  is  broken,  what  must  be 
done  ? 

Answer.  If  the  valve-stem  is  broken  outside  of  the  steam-chest  the 
valve  must  be  moved  to  cover  both  ports  and  then  fastened  in  that  posi- 
tion and  the  engine  disconnected  on  that  side,  as  already  described.  If 
the  break  is  inside,  the  steam-chest  cover  must  be  taken  off  and  the  valve 
secured,  with  blocking  or  otherwise,  so  as  to  cover  the  ports,  and  the 
opening  for  the  valve-stem  must  be  closed  with  a wooden  plug  inserted 
from  the  inside  of  the  chest,  so  that  the  steam  pressure  will  not  blow  it  out. 


Accidents  to  Locomotives. 


661 


If  the  valve  is  broken  a wooden  board,  1 inch  thick  should  be  placed 
over  the  valve-face  and  blocks  placed  on  top  of  it,  so  that  when  the  steam- 
chest  cover  is  screwed  down  it  will  hold  the  board  on  to  the  valve-face. 

Question  896.  If  the  valve-face  is  broken,  what  should  be  done  ? 

Answer.  If  the  metal  of  the  face  is  broken,  so  that  the  front  port  can- 
not be  closed,  then  the  piston  should  be  fastened  at  the  back  end  of  the 
cylinder  and  the  valve  should  be  secured,  so  as  to  cover  the  exhaust  and 
the  back  steam-ports,  that  side  of  the  engine  being  disconnected.  If  the 
back  steam-port  is  the  one  injured,  then  the  piston  and  valve  should  be 
placed  in  the  reverse  position.  If  either  of  the  bridges  between  the  ports 
are  broken,  then  the  valve  should  cover  all  of  them. 

Question  897.  In  case  the  throttle-valve  should  fail,  what  should  be 
done  ? 

Answer.  If  such  an  accident  occurs,  especially  if  it  happens  about  a 
station,  it  is  attended  with  great  danger.  If  it  is  found  that  steam  cannot 
be  shut  off  from  the  cylinders  with  the  throttle-valve,  all  the  brakes  should 
be  applied  and  the  reversing  lever  should  be  placed  in  the  middle  of  the 
sector.  If  this  does  not  prevent  the  engine  from  moving,  the  reversing 
lever  should  be  alternately  thrown  into  forward  and  then  into  back  gear, 
and  at  the  same  time  every  aperture,  such  as  the  safety-valve  and  heater- 
cocks,  should  be  opened,  and  every  means  be  taken  to  cool  the  boiler  as 
quickly  as  possible.  The  fireman  should  open  the  furnace  door,  close  the 
ash-pan  dampers,  and  start  the  blower  so  as  to  draw  a strong  current  of 
cold  air  into  the  furnace  and  through  the  tubes.  At  the  same  time  the 
injector  should  be  started  and  the  fire  drawn  as  quickly  as  possible.  After 
the  boiler  is  cooled,  the  cover  of  the  steam-dome  maybe  removed  arid  the 
valve  examined  if  the  defect  cannot  be  discovered  in  any  other  way.  Of 
course  if  the  accident  occurs  on  the  open  road,  the  train  must  be  at  once 
protected  by  sending  out  signals  in  each  direction. 

Question  898.  What  must  be  done  in  case  a coupling  breaks? 

Answer.  When  a coupling  between  the  cars  or  tender  breaks,  if  the 
front  end  of  the  train  is  immediately  stopped,  there  will  be  danger  that 
the  back  end  of  it,  which  is  broken  loose,  will  run  into  the  front  end,  and 
thus  do  great  damage.  As  it  always  occurs,  when  a coupling  of  a passen- 
ger train  breaks,  that  the  signal  bell  in  the  cab  is  rung,  the  first  impulse  of 
the  runner  under  such  circumstances  is  to  stop  the  engine.  He  should, 
however,  be  careful  not  to  do  so  if  on  shutting  off  steam  he  finds  that  the 
train  has  broken  in  two,  but  should  at  once  open  the  throttle  in  order  to 
get  the  front  end  of  the  train  out  of  the  way  of  the  rear  end.  The  ease 


662 


Catechism  of  the  Locomotive. 


with  which  the  speed  of  a train  is  arrested  with  continuous  brakes  may 
increase  the  danger  of  accident  from  this  cause.  Usually  an  engineer 
learns  by  the  sudden  start  of  the  engine  that  the  train  has  separated,  and 
when  that  occurs  he  should  never  apply  the  brakes. 

QUESTION  899.  If  from  any  cause  the  supply  of  water  in  the  tender 
becomes  exhausted ',  what  must  be  done  ? 

Answer.  It  is  best,  if  it  can  be  done  without  risk  of  injury  to  the 
engine,  to  run  the  train  on  a side  track  and  then  draw  the  fire.  If  no 
water  can  be  obtained  near  enough  to  supply  the  tender  with  buckets, 
help  must  be  sent  for ; but  if  there  is  a well,  stream,  or  pond  of  water 
near,  the  tender  can  be  partly  filled  by  carrying  water. 

Question  900.  In  case  an  engine  becomes  blockaded  in  a snow-storm 
with  plenty  of fuel ',  but  runs  out  of  water , what  can  be  done  ? 

Answer.  Snow  should  be  shoveled  into  the  tender  and  steam  admitted 
through  the  heater  cocks  so  as  to  melt  the  snow. 

Question  901.  If  a locomotive  without  an  injector  should  be  obstructed 
in  a snow-storm  or  in  any  other  way  so  that  it  could  not  move , and  there- 
fore could  not  work  the  pumps,  what  should  be  done  in  case  the  water  in  the 
boiler  should  get  low? 

Answer.  The  weight  of  the  engine  should  be  lifted  off  from  the  main 
driving-wheels  and  the  coupling-rods  disconnected  from  the  main  crank- 
pin,  so  that  the  main  wheels  can  turn  without  moving  the  engine.  These 
can  then  be  run  and  the  pumps  thus  be  worked.  The  weight  can  usually 
be  most  conveniently  taken  off  from  the  main  wheels  by  running  the 
trailing  wheels  on  wooden  blocks,  and  thus  raising  up  the  back  end  of  the 
engine. 

Question  902.  If  it  is  impossible,  in  a snow-storm  or  in  very  cold 
weather,  to  keep  steam  in  the  boiler  without  danger,  what  should  be  done  ? 

Answer.  Draw  the  fire,  blow  all  the  water  out  of  the  boiler,  empty  the 
tanks,  disconnect  the  hose,  and  slacken  up  the  joints  in  the  pumps  and 
injector  so  that  all  the  water  in  them  can  escape,  and  thus  prevent  them 
from  freezing  up. 


CHAPTER  XXXVII. 


ACCIDENTS  AND  INJURIES  TO  PERSONS. 

Question  903.  In  case  an  accident  occurs  and  one  or  more  persons  are 
seriously  injured,  what  can  be  done  by  those  present  ? 

Answer.  In  such  cases  it  very  often  happens  that  with  knowledge,  and 
sufficient  coolness  to  apply  that  knowledge,  one  or  more  non-medical 
persons  who  are  present  when  an  accident  occurs  can  do  as  much  or  more 
toward  saving  life  and  allaying  pain  before  a doctor  comes  than  he  can 
afterward.  The  following  cases  cited  by  Dr.  Howe  in  his  book  on 
“ Emergencies,  and  How  to  Treat  Them,  ” will  illustrate  this  : 

“ Case  1. — A machinist  was  admitted  to  a New  York  hospital  suffering 
from  wounds  of  the  wrist  and  palm  of  the  hand.  On  arriving  at  the 
hospital  the  entire  clothing  on  one  side  of  his  body  was  saturated  with 
blood,  from  the  loss  of  which  he  was  partly  insensible.  On  making  an 
examination,  it  was  found  by  the  surgeon  that  a folded  handkerchief  was 
bandaged  over  the  centre  of  the  wrist,  and  that  the  wound  in  the  palm  of 
the  hand  was  untouched.  The  pad  was  placed  on  the  wrist,  as  if  the 
greatest  care  had  been  exercised  to  avoid  pressing  on  either  of  the  two 
arteries.  The  bleeding  in  this  case  could  easily  have  been  controlled  if 
the  bandage  and  pad  had  been  properly  applied.  The  patient,  however, 
developed  erysipelas,  and  not  having  sufficient  vitality  to  carry  him 
through,  died  the  fifth  day.” 

“ Case  2. — A laborer  fell  from  the  front  platform  of  a car  at  Harlem  and 
had  his  right  foot  crushed  by  one  of  the  wheels.  An  ordinaiy  bandage 
was  placed  on  the  limb,  without  any  compress  over  the  vessels.  In  bring- 
ing the  man  to  the  hospital,  the  rough  jolting  of  the  carriage  set  the 
wound  bleeding,  and  by  the  time  he  reached  his  destination  he  was 
apparently  lifeless.  The  vessels  were  tied  and  stimulants  administered, 
but  he  never  rallied.  Death  occurred  six  hours  after  his  admission.  His 
injuries,  independent  of  the  bleeding,  might  indeed  have  terminated  his 
life  ; still  the  chances  would  have  been  in  his  favor  if  a compress  had  been 
applied  to  the  limb  to  prevent  bleeding.  The  fact  that  such  a thing  was 
not  done  shows  either  culpable  negligence  or  deplorable  ignorance.” 


664 


Catechism  of  the  Locomotive. 


Many  similar  cases  constantly  occur  where  a little  intelligent,  timely 
action  of  those  present  would  save  the  life  of  an  injured  person  who, 
without  such  help,  must  die  before  professional  surgical  aid  can  be 
obtained. 

Question  904.  When  it  is  found  that  one  or  more  persons  are  seriously 

injured , what  is  the  first  thing  to  be  done  ? 

Answer . The  first  thing  to  do  is  to  extricate  the  person  or  persons 
from  the  danger,  and  at  the  same  time  send  a messenger  for  a doctor. 
If  it  is  doubtful  if  one  can  be  obtained  by  sending  in  one  direction,  send 
two  or  more  messengers  in  different  directions. 

Question  905.  To  what  kind  of  injuries  are  locomotive  runners  and 
other  persons  employed  or  travelling  on  railroads  exposed  ? 

Answer.  They  are  liable  to  be  bruised  or  crushed  in  case  of  collision 
or  running  off  the  track,  or  of  injury  from  falling  off  the  train,  or  of  being 
run  over  by  a moving  train.  Brakemen  and  others  whose  duty  it  is  to 
couple  cars  are  liable  to  have  their  hands,  arms,  or  bodies  crushed  between 
the  cars,  and  locomotive  engineers  are  sometimes  burned  or  scalded  if  an 
accident  happens  to  their  engines.  Train-men  are  also  frequently  exposed 
to  very  great  cold  in  winter  and  heat  in  summer,  and  are  thus  liable  to  be 
frost-bitten  or  sun-struck.  Passengers  are  seldom  injured  excepting 
through  their  own  carelessness,  unless  in  cases  of  collision  or  running  off 
the  track  and  the  destruction  of  the  cars.  Strangers  and  railroad  em- 
ployees are  frequently  run  over  by  trains  while  walking  or  being  on  rail- 
road tracks.  It  is  estimated  that  from  five  to  six  thousand  people  are 
killed  and  wounded  every  year  from  “being  on”  railroad  tracks.  Fre- 
quent accidents  occur  to  deaf  people  in  this  way,  and  it  is  not  very  unusual 
to  hear  of  train-men  who  sit  on  the  main  track  at  night  while  their  trains 
are  waiting  on  the  side-track  for  another  train  to  pass,  go  to  sleep  while 
in  that  position,  and  then  are  run  over  by  the  passing  train. 

Question  906.  How  can  accidents  from  being  on  the  track  be 
avoided? 

Answer.  The  obvious  way  is  to  stay  off  of  railroad  tracks,  unless  called 
there  by  duty,  then  to  stay  there  as  short  a time  as  possible,  and  while 
there  exercise  the  utmost  vigilance  to  keep  out  of  the  way  of  moving 
engines  and  cars.  It  should  be  remembered  that  there  is  comparatively 
little  danger  to  persons  on  engines  or  cars,  but  A railroad  track  IS 
ALMOST  AS  DANGEROUS  AS  A BATTLEFIELD  TO  THOSE  ON  FOOT  OR 

who  are  travelling  in  wagons  or  carriages.  It  should  be  a uni- 
versal rule  with  every  person,  whether  a railroad  employee  or  not,  always 


Accidents  and  Injuries  to  Persons. 


665 


TO  COME  TO  A FULL  STOP  BEFORE  CROSSING  OR  GOING  ON  A RAIL- 
ROAD track.  It  will  be  repeated  here  that  if  this  rule  was  universally 
adopted  many  lives  would  be  saved  and  much  suffering  avoided. 

QUESTION  907.  When  persons  are  crushed  or  dangerously  wounded, 
what  are  the  chief  immediate  sources  of  da7iger  and  death  when  their 
wounds  are  not  necessarily  fatal? 

Answer.  First,  excessive  bleeding  in  case  an  artery  is  ruptured  ; second, 
the  shock  to  the  whole  system,  from  which  the  sufferer  may  not  have  the 
strength  to  recover. 

Question  908.  When  does  bleeding  from  a wound  become  dangerous  ? 

Answer.  Profuse  bleeding  is  always  dangerous,  but  it  should  be  re- 
membered that  bleeding  occurs  from  two  sources  ; first,  from  the  arteries, 
which  are  the  vessels  which  convey  the  blood  from  the  heart,  and  second, 
from  the  veins,  through  which  the  blood  flows  back  to  the  heart.  The 
first  is  called  arterial  bleeding  and  the  second  venous  bleeding.  Now  it 
must  be  remembered  that  the  heart  is  the  great  force-pump  of  the  body, 
and  that  it  supplies  all  parts  of  the  body  with  blood,  somewhat  as  the 
feed-pump  of  a locomotive  supplies  the  boiler  with  water.  The  arteries 
referred  to  fulfil  the  same  purpose  that  the  feed-pipe  does  to  a locomotive 
pump — they  convey  the  fluid  from  the  pump  to  the  place  where  it  is 
needed.  Now  the  blood  is  forced  into  these  arteries  with  a certain  amount 
of  pressure,  so  that  if  any  of  them  are  cut  or  injured  the  blood  will  flow 
out  in  a jet  or  spurt  just  as  the  water  will  escape  from  a feed-pipe  if  that 
is  ruptured.  The  blood  which  flows  through  the  veins  back  to  the  heart 
may,  on  the  other  hand,  be  compared  to  the  water  in  the  supply-pipes  of 
a locomotive  pump — that  is,  there  is  very  little  pressure  on  it,  and  there- 
fore if  they  are  injured  the  flow  of  blood  from  them  is  less  rapid  than 
from  the  arteries.  It  will  therefore  be  seen  that  arterial  bleeding  is 
much  more  dangerous,  because  the  blood  flows  from  them  under  a 
pressure. 

Question  909.  How  can  arterial  bleeding  be  distinguished  from  venous 
bleeding  ? 

Answer.  The  blood  is  of  a bright  scarlet  color,  and  is  forced  out  in 
successive  jets ; each  jet  corresponds  with  the  movements  of  the  heart. 
This  characteristic  spurting  is  caused  by  the  intermittent  force-pump 
action  of  the  heart,  driving  out  the  blood.  Venous  bleeding  is  distin- 
guished from  arterial  by  the  dark  blue  or  purple  color  of  the  blood  when 
flowing  from  the  wound.  It  never  flows  in  repeated  jets,  but  oozes  slowly 
from  the  wounded  surfaces.  Venous  blood  is  travelling  toward  the  heart, 


066 


Catechism  of  the  Locomotive. 


and  there  is  consequently  little  force  behind  to  cause  a more  rapid  flow. 
This  form  of  bleeding  is  comparatively  harmless,  unless  occurring  from 
very  large  veins.* 

QUESTION  910.  How  can  the  bleeding  be  stopped  in  case  an  artery  is  but 
or  ruptured? 

Answer.  The  most  efficient  and  available  method  is  the  application  of 
pressure  on  the  artery  between  the  wound  and  the  heart.  Under 
ordinary  circumstances  this  can  be  most  effectually  done  by  simply  pass- 
ing a handkerchief  around  the  limb  above  the  wound,  or  between  it  and 
the  heart;  the  ends  of  the  handkerchief  are  then  tied  together.  A pad  is 
then  made,  either  of  cloth  rolled  up,  cotton  waste,  a piece  of  wood,  or  a 
round  stone  about  the  size  of  a horse-chestnut  well  wrapped,  or  any  sub- 
stance from  which  a firm  pad  can  be  quickly  made,  which  is  placed  over 
the  artery.  The  handkerchief,  folded  in  the  form  of  a bandage,  is  placed 
over  the  pad  and  passed  around  the  limb  and  tied  on  the  opposite  side  to 
the  pad,  and  then  a rounded  stick  about  six  inches  long  and  three-fourths 
of  an  inch  in  thickness  is  passed  under  the  knot,  so  that  the  handkerchief 
may  be  twisted  sufficiently  tight  to  stop  the  bleeding  by  pressing  the  pad 
upon  the  artery ; the  twisting  of  the  stick  and  the  pressure  upon  the  artery 
should  only  be  sufficient  to  stop  the  bleeding  from  the  artery  ; too  much 
pressure  or  twisting  would  be  painful,  and  might  produce  other  serious 
consequences.  While  the  bandage  is  being  prepared,  some  one  should 
compress  the  artery  with  his  fingers  or  thumb  so  as  to  prevent  as  much 
loss  of  blood  as  possible. 

Question  911.  What  is  the  position  of  the  arteries  in  the  body  and 
how  can  their  location  be  known  ? 

Answer.  The  position  of  the  principal  arteries  is  shown  in  fig.  488. 
They  proceed  from  the  heart,  h , with  branches,  a a and  b b,  which  extend 
along  each  limb.  These  branches  subdivide  again  below  the  knees  and 
elbows,  and  again  in  the  hands  and  feet.  The  position  of  the  arteries  can 
be  felt  by  their  pulsation  at  almost  any  part  of  them,  but  at  some  places 
they  are  covered  so  thickly  by  the  muscles,  that  it  is  more  difficult  to  feel 
their  throb  than  it  is  where  they  are  near  the  surface.  At  a and  a they 
are  near  the  surface  of  the  body,  and  also  at  the  thighs  at  b b,  and  again 
at  c c,  immediataly  back  of  the  knees,  and  in  the  wrists  at  d d.  At  these 
places  the  pulsations  of  the  blood  can  be  distinctly  felt. 

QUESTION  912.  In  case  of  a wound  and  rupture  of  the  arteries  in  the 
arm , what  should  be  done  ? 


“ Emergencies  and  How  to  Treat  Them,”  by  Joseph  W.  Howe,  M.  D. 


Accidents  and  Injuries  to  Persons. 


66' 


Answer.  The  artery  should  be  firmly  compressed  at  a with  the  thumb 
until  a bandage  and  pad  can  be  prepared.  The  pad  should  then  be 
applied  over  the  artery  and  compressed  as  explained  in  answer  to  Question 
910.  The  bleeding  can  also  be  stopped  by  placing  a round  piece  of  wood 
or  other  form  of  pad  between  the  arm  at  a and  the  body  and  then  tying 


the  arm  tightly  against  the  body,  so  that  the  pad  will  be  pressed  against 
the  arm. 

Question  913.  In  case  of  rupture  to  an  artery  below  the  knee,  where 
should  the  pressure  be  applied? 

Answer.  The  artery  approaches  near  the  surface  at  c c,  immediately 
back  of  the  knee,  where  it  is  represented  in  dotted  lines,  in  fig.  488. 
Pressure  should  therefore  be  applied  at  that  point  first  with  the  thumb 


668 


Catechism  of  the  Locomotive. 


until  a bandage  can  be  applied.  The  bleeding  can  also  be  stopped  by 
elevating  the  leg  and  allowing  it  to  rest  on  the  back  of  a chair  or  other 
similar  support.  The  weight  of  the  leg  will  then  bring  sufficient  pressure 
on  the  artery  to  stop  the  bleeding.  A towel  or  other  soft  material  should 
be  placed  over  the  back  of  the  chair,  so  that  the  pressure  will  not  be  too 
painful  to  the  sufferer. 

Question  914.  If  an  artery  is  ruptured  in  the  thigh  above  the  knee, 
where  should  the  pressure  be  applied  ? 

Answer.  In  the  thigh,  at  b , where  the  beating  or  pulsations  in  the 
artery  can  be  distinctly  felt.  The  reader  should  familiarize  himself  with 
the  position  of  the  arteries  by  feeling  their  location  in  his  own  body.  By 
doing  so  he  may  be  able  to  save  his  own  life,  the  life  of  a companion  or 
other  person  in  case  of  accident,  whereas  without  such  knowledge  the 
injured  person  might  die. 

Question  915.  After  the  arterial  bleeding  has  been  stopped,  if  blood 
should  continue  to  ooze  out  of  the  wound,  what  should  be  done  ? 

Answer.  The  wound  should  be  filled  with  lint  or  clean  cotton  waste ; 
and  the  limb  then  be  bandaged  by  beginning  at  its  extremity  and  wrap- 
ping the  bandage  closely  and  evenly  around  it,  so  as  to  bring,  as  nearly  as 
possible,  an  equal  pressure  on  the  whole  of  it.  Bandaging  the  limb  in 
this  way  up  to  the  point  where  the  pressure  is  applied  to  the  artery,  will 
prevent  swelling,  and  the  veins  will  be  compressed  so  that  the  blood  will 
not  flow  from  their  torn  extremities. 

Question  916.  When  the  bleeding  has  been  stopped,  what  should  be  done  f 

Answer.  The  injured  person  should  be  laid  in  as  comfortable  a place 
as  can  be  procured  for  him,  and  should  be  given  a moderate  drink  of 
water.  If  much  exhausted,  two  or  three  tablespoonsful  of  brandy  or 
whiskey,  mixed  with  an  equal  quantity  of  water,  should  be  given  first,  and 
smaller  quantities,  of  not  more  than  a tablespoonful  at  a time,  should 
then  be  given  every  half  hour.  Usually  wounded  persons  are  given  too 
much  stimulants,  so  that  frequently  they  are  injured  more  than  they  are 
benefited  thereby. 

After  a person  has  lost  much  blood,  he  feels  an  intolerable  thirst,  but  if 
too  much  water  is  given  him,  he  is  apt  to  become  sick  and  vomit,  which 
weakens  him  still  more.  It  is  therefore  best  to  give  him  very  little  water, 
say  a spoonful  at  a time,  after  the  first  drink,  or  if  ice  can  be  obtained, 
give  the  sufferer  pieces  of  ice  frequently  which  can  be  allowed  to  melt  in 
his  mouth. 

QUESTION  917.  In  case  any  bones  are  broken . what  should  be  done  ? 


Accidents  and  Injuries  to  Persons. 


669 


Answer.  The  limb  should  be  supported  as  comfortably  as  possible  until 
a doctor’s  services  can  be  obtained.  There  is  danger  with  a broken 
limb  that  the  bones  will  protrude  through  the  flesh  and  skin,  to  avoid 
which  the  limb  should  be  placed  in  a natural  position  and  laid  on  a pillow, 
car  cushion,  or  other  soft  object.  This  should  then  be  wrapped  around 
the  limb  and  tied  in  this  position,  so  as  to  prevent  any  movement  of  the 
broken  bones.  A temporary  splint  may  be  made  by  tying  an  umbrella  or 
light  strips  of  wood  to  the  broken  limb,  or  by  tying  an  injured  leg  to  the 
other  which  is  uninjured. 

Question  918.  When  a person  is  insensible , what  should  be  done  for 
him  ? 

Answer.  Lay  him  down  in  as  comfortable  a place  as  the  circumstances 
will  permit,  and  protect  him  from  cold,  rain,  or  hot  sun,  as  may  be  needed. 
A common  error  is  to  place  injured  and  insensible  persons  in  an  erect  posi- 
tion or  in  a chair.  If  he  is  insensible  he  should  always  be  laid  down  with 
his  head  slightly  lower  than  his  body.  Then  water  should  be  dashed  two 
or  three  times  on  his  face,  and  warm  bricks,  stones,  or  pieces  of  iron,  such 
as  coupling  links  or  pins  applied  to  his  feet,  and  in  the  arm-pits  and 
between  the  thighs,  being  careful  that  the  warm  objects  applied  are  not 
hot  enough  to  burn.  Then  cover  the  person  with  blankets,  heavy  coats, 
or  anything  else  which  will  keep  him  warm.  Wounded  persons  soon 
become  cold  and  chilled,  the  effects  of  which  are  very  injurious,  and  there- 
fore especial  pains  should  be  taken  to  keep  them  warm.  In  very  cold 
weather  there  is  great  danger  that  injured  persons  will  be  frost-bitten, 
which  must  be  carefully  guarded  against. 

Question  919.  What  is  meant  by  “shock”  or  “ collapse  ” ? 

Answer.  “Shock  ” is  a condition  in  which  there  is  more  or  less  dimin- 
ished energy  of  the  heart  and  circulation,  and  is  the  result  of  a severe  impres- 
sion made  upon  the  nervous  system,  produced  by  either  a physical  injury 
or  a mental  emotion.  The  majority  of  cases  met  with  are  the  result  of 
extensive  burns  or  other  grave  injuries,  particularly  those  produced  by 
gunshot  wounds  and  railway  accidents,  which  are  generally  associated 
with  great  laceration  and  crushing  of  the  tissues,  and  mental  excitement. 
Severe  cases  of  “ shock  ” may  be  produced  by  fright  alone.  “ Shock'’  may 
be  of  a very  mild  character,  as  the  result  of  a trifling  injury  or  fright,  the 
symptoms  being  hardly  noticeable,  of  short  duration,  and  demanding  no 
treatment ; or,  it  may  assume  a form  which  is  rapidly  fatal.* 


* From  a Manual  of  Instruction  in  the  Principles  of  “ Prompt  Aid  to  the  Injured,”  by  Alvah 
H Doty,  M.D.,  published  by  D.  Appleton  & Co.,  New  York. 


670 


Catechism  of  the  Locomotive. 


Question  920.  What  are  the  symptoms  of  “ shock  ” ? 

Answer.  In  some  cases,  when  the  injury  is  slight,  the  symptoms  may 
be  hardly  apparent,  or,  only  a pale  face  and  a weak  and  rapid  pulse,  a 
slight  nausea,  and  a general  sense  of  prostration  may  be  produced.  In 
cases  of  severe  injury,  such  as  might  be  caused  by  a serious  railroad  acci- 
dent, the  person  injured  is  conscious,  but  dazed  and  flighty,  cannot  realize 
his  condition,  and  apparently  only  appreciates  loud  and  repeated  ques- 
tions; articulation  is  difficult  although  there  is  no  paralysis  present. 
The  sensibility  to  pain  may  be  so  blunted  that  an  operation  can  be  per- 
formed without  the  patient  knowing  it.  The  extreme  pallor  and  coldness 
of  the  skin  are'  startling  ; the  surface  of  the  body  is  covered  with  moisture; 
large  beads  of  sweat  cover  the  forehead ; the  pulse  at  the  wrist  may  be 
lost,  or,  if  perceptible,  is  weak,  rapid,  and  irregular ; the  features  are 
shrivelled,  particularly  about  the  nose,  which  appears  pinched  ; the  eyes 
are  lustreless,  sunken  deeply  in  the  sockets,  and  turned  upward,  the 
pupils  being  generally  dilated.  There  is  no  other  condition  which  so 
closely  resembles  death.  The  symptoms  may  continue  for  a few  minutes 
or  a number  of  hours,  and  often  end  in  death. 

Question  921.  What  should  be  done  for  a person  in  the  condition 
described? 

Answer.  Those  in  attendance  should  at  once  loosen  the  clothing,  or 
cut  it  open  rather  than  have  too  much  delay,  and  make  a rapid  examina- 
tion to  ascertain  whether  severe  bleeding  exists,  or  if  one  or  more  of  the 
bones  in  the  legs  or  arms  are  broken.  If  there  is  bleeding  it  should  be 
stopped  as  already  directed,  or  if  any  of  the  bones  are  broken  a temporary 
splint  should  be  applied  as  quickly  as  possible.  The  patient  should  then 
be  carried  to  the  most  convenient  and  sheltered  place  within  reach.  While 
being  removed  the  head  should  be  as  low  as,  or  somewhat  lower,  than  the 
body,  or  the  extremities  may  be  slightly  elevated,  so  as  to  favor  the  flow 
of  blood  toward  the  brain.  If  possible,  four  persons  should  assist  to  carry 
the  patient,  one  for  each  extremity  and  the  contiguous  portions  of  the 
body.  His  clothing  should  be  removed,  and  he  should  be  made  as  com- 
fortable . as  possible,  and,  as  has  been  explained,  kept  warm  by  proper 
covering  and  applying  bottles  of  hot  water,  warm  coupling-pins,  links,  or 
other  pieces  of  iron,  or  bricks,  or  stones.  These  should  be  placed  about 
the  arms  and  legs,  inside  the  thighs,  and  under  the  arm-pits  and  about  the 
body,  but  not  about  the  head,  as  this  might  favor  congestion  when  re- 
action occurs.  If  heat  cannot  be  applied  as  described,  the  injured  person 
should  be  rubbed  in  order  to  excite  circulation.  If  able  to  swallow,  he 


Accidents  and  Injuries  to  Persons. 


671 


should  be  given  about  two  teaspoonsful  of  whisky  or  brandy,  with  a small 
amount  of  hot  water,  or,  still  better,  hot  milk ; this  may  be  repeated  every 
ten  or  fifteen  minutes,  until  four  or  five  doses  have  been  taken,  or  reaction 
becomes  apparent.  When  the  latter  occurs,  the  stimulant  should  be 
diminished  or  discontinued.  When  reaction  occurs,  the  color  and  warmth 
gradually  return  to  the  skin,  the  eyes  are  brighter,  and  the  symptoms  indi- 
cate an  approach  to  the  normal  condition.  Vomiting  is  regarded  as  a 
favorable  symptom  and  generally  denotes  reaction.  This  does  not  always 
insure  safety,  and  the  sufferer  should  be  carefully  watched.  When  re- 
action has  taken  place  warm  beef-tea,  broth,  or  milk  should  be  given  in 
small  quantities.* 

All  assistance  and  attention  should  be  given  to  a wounded  person  with 
the  least  noise  and  excitement,  and  all  crowds  and  idle  spectators  should 
be  driven  away  and  every  effort  made  to  keep  the  sufferer  comfortable 
and  quiet. 

Question  922.  If  a person  is  crushed  or  severely  burned , what  should 
be  done  ? 

Answer.  The  immediate  danger  from  such  injuries  arises  from  the 
“ shock”  to  the  system.  It  is  usually  best  to  bandage  the  part  which  is 
crushed  until  surgical  aid  can  be  obtained,  and  the  sufferer  treated  as 
explained  in  answer  to  Question  921. 

Question  923.  What  should  be  done  for  a person  who  has  been  burned 
or  scalded ? 

Answer.  The  wound  should  be  dusted  with  bicarbonate  of  soda  (com- 
mon baking  soda,  not  washing  soda),  wheat  flour,  starch,  chalk,  or  char- 
coal, and  then  dressed  with  lint  or  clean  cotton  waste  and  loosely 
bandaged.  Vaseline,  cosmoline,  olive  or  linseed  oil,  or  molasses,  may  be 
employed  for  dressing  burns  or  scalds.  If  blisters  are  produced  the  cloth- 
ing should  never  be  forcibly  removed  from  them,  but  carefully  cut  off 
with  scissors  as  close  to  the  burn  as  possible.  The  small  pieces  adhering 
to  the  skin  may  be  afterwards  washed  away  with  warm  water,  or  softened 
with  oil  and  detached  later.  If  the  blisters  are  large,  they  should  be 
pricked  at  their  lowest  part  and  the  contents  allowed  to  escape.  The  oily 
substances  already  recommended  should  then  be  applied  as  described.* 

If  the  injury  should  be  severe,  a shivering,  followed  by  depression,  is 
very  likely  to  come  on.  To  check  this,  warmth  in  the  form  of  hot  appli- 
cations and  stimulants  should  be  used,  as  already  explained. 

Question  924.  What  should  be  done  for  a frost-bite ? 

* From  “ Prompt  Aid  to  the  Injured,”  by  Alvah  H.  Doty,  M.  D, 


672 


Catechism  of  the  Locomotive. 


Answer.  Warmth  should  be  applied  to  the  frozen  part  very  gradually 
by  rubbing  with  snow  or  pouring  cold  water  on  it.  The  occurrence  of 
stinging  pain,  with  a change  in  color,  is  a signal  to  stop  all  rubbing  or 
other  measure  which  might  excite  inflammation.  If  the  frozen  part  turns 
black  the  next  day,  a poultice  should  be  applied. 

If  persons  exposed  to  the  cold  become  very  much  exhausted  or  sleepy, 
stimulants  should  be  given,  as  explained  in  answer  to  Question  921,  and 
the  body  briskly  rubbed  with  the  hands  and  warm  flannel  or  other  woolen 
material. 

Question  925.  How  should  a person  be  treated  who  has  been  sun- 
struck  ? 

Answer.  Apply  cold  water  or  ice  to  the  head,  place  the  sufferer  in  a 
cool  place,  and  make  him  comfortable.  After  being  sun-struck  the  person 
should  not  work  for  some  days  or  weeks  thereafter,  until  his  health  and 
strength  are  fully  recovered. 

Question  926.  How  should  persons  who  have  been  under  water  for  a 
short  time,  and  unconscious  when  taken  out,  be  treated? 

Answer.  Persons  who  have  been  under  water  for  four  or  five  minutes 
or  more  are  not  usually  restored  to  life,  although  numerous  cases  are 
recorded  where  resuscitation  was  effected  after  an  interval  of  twenty 
minutes.  If  they  have  been  under  water  but  a few  moments,  the  water, 
mud,  and  mucus  should  be  removed  from  the  mouth  and  nose,  and  the 
tongue  should  be  pulled  forward,  and  the  person  should  be  turned  on  his 
side,  face  downward,  to  allow  the  water  to  escape.  He  should  then  again 
be  turned  on  his  back,  while  the  hands  of  the  attendant  are  placed  on  the 
belly  and  pressure  directed  upward  and  inward  toward  the  diaphragm. 
This  movement  tends  to  stimulate  respiration,  and  should  be  repeated 
two  or  three  times  at  intervals  of  two  or  three  seconds.  The  mouth  in 
the  meantime  should  be  kept  open  by  a cork  or  piece  of  wood,  or  a knot 
tied  in  a handkerchief,  etc.,  in  order  that  the  passage  of  air  to  the  lungs 
should  not  be  interfered  with.  Tickling  the  nose  with  a feather  or  straw 
also  stimulates  breathing.  When  breathing  commences  and  consciousness 
returns,  the  patient  should  be  carefully  divested  of  all  wet  clothing  as  soon 
as  possible,  be  well  rubbed,  and  wrapped  in  warm  covering,  and  stimulants 
be  given  in  the  manner  already  described  for  cases  of  “shock.” 

If  these  simple  measures  are  productive  of  no  good  result  after  a short 
trial,  artificial  respiration  should  be  at  once  resorted  to. 

Before  artificial  respiration  is  begun,  the  patient  should  be  stripped  to 
the  waist,  and  the  clothing  around  the  latter  part  should  be  loosened  so 


Accidents  and  Injuries  to  Persons. 


673 


that  the  necessary  manipulations  of  the  chest  may  not  be  interfered  with. 

The  water  and  mucous  having  been  removed  from  the  mouth  and 
throat  as  described,  the  patient  is  to  be  placed  on  his  back,  with  a roll 
made  of  a coat  or  shawl  under  the  shoulders ; the  tongue  should  then  be 
drawn  forward  and  retained  by  a handkerchief,  which  is  placed  across  the 
extended  organ  and  carried  under  the  chin,  then  crossed  and  tied  at  the 
back  of  the  neck.  An  elastic  band  or  small  rubber  tube  or  suspender  may 
be  substituted  for  the  same  purpose.  If  no  other  means  can  be  made 
available,  a hat  or  scarf-pin  may  be  thrust  vertically  through  the  end  of  the 
tongue  without  permanent  injury  to  this  organ.  The  attendant  should  kneel 
at  the  head  and  grasp  the  elbows  of  the  patient  and  draw  them  upward 
until  the  hands  are  carried  above  the  head,  and  kept  in  this  position  until 
one,  two,  three  can  be  slowly  counted.  This  movement  elevates  the  ribs, 
expands  the  chest,  and  creates  a vacuum  in  the  lungs  into  which  the  air 
rushes,  or,  in  other  words,  the  movement  produces  inspiration.  The 
elbows  are  then  slowly  carried  downward,  placed  by  the  side,  and  pressed 
inward  against  the  chest,  thereby  diminishing  the  size  of  the  latter  and 
producing  expiration.  These  movements  should  be  repeated  about  fifteen 
times  during  each  minute  for  at  least  two  hours,  provided  no  signs  of 
animation  present  themselves. 

If  after  using  the  above  method  evidence  of  recovery  appears,  such  as 
an  occasional  gasp  or  muscular  movement,  the  efforts  to  produce  artificial 
respiration  must  not  be  discontinued,  but  kept  up  until  respiration  is  fully 
established.  All  wet  clothing  should  be  removed,  the  patient  rubbed  dry, 
and  if  possible  placed  in  bed,  where  warmth  and  stimulants  can  be  pro- 
perly administered.* 

* From  “ Prompt  Aid  to  the  Injured,”  by  Alvah  H.  Doty,  M.  D. 


THE  END. 


674 


Appendix  I. 


PROPERTIES  OF  SATURATED  STEAM. 


Total  pressure 

per  sq.  inch, 

measured  from 

a vacuum 

Pressure  above 

the  atmosphere 

Sensible  temper- 

ature in  Fahr- 
enheit degrees. 

Total  heat  in  de- 

grees from  ze- 
ro of  Fahren- 
heit   

Weight  of  one 
cubic  foot  of 
Steam 

Relative  volume 
of  the  steam 
compared  with 
the  water  from 
which  it  was 
raised 

Lb. 

Lb. 

Deg. 

Deg. 

Lb. 

1 

102.1 

1144.5 

.0030 

20582 

2 

• V • • 

126.3 

1151.7 

.0058 

10721 

3 

• • • 

141.6 

1156.6 

.0085 

7322 

4 

153.1 

1160.1 

.0112 

5583 

5 

162.3 

1162.9 

.0138 

4527 

6 

170.2 

1165.3 

.0163 

3813 

7 

176.9 

1167.3 

.0189 

3298 

8 

182.9 

1169.2 

.0214 

2909 

9 

188.3 

1170.8 

.0239 

2604 

10 

193.3 

1172.3 

.0264 

2358 

11 

197.8 

1173.7 

.0289 

2157 

12 

202.0 

1175.0 

.0314 

1986 

13 

205.9 

1176.2 

.0338 

1842 

14 

.... 

209.6 

1177.3 

.0362 

1720 

14.7 

0. 

212.0 

1178.1 

.0380 

1642 

15 

.3 

213.1 

1178.4 

.0387 

1610 

16 

1.3 

216.3 

1179.4 

.0411 

1515 

17 

2.3 

219.6 

1180.3 

.0435 

1431 

18 

3.3 

222.4 

1181.2 

.0459 

1357 

19 

4.3 

225.3 

1182.1 

.0483 

1290 

20 

5.3 

228.0 

1182.9 

.0507 

1229 

21 

6.3 

230.6 

1183.7 

.0531 

1174 

22 

7.3 

233.1 

1184.5 

.0555 

1123 

23 

8.3 

235.5 

1185.2 

.0580 

1075 

24 

9.3 

237.8 

1185.9 

.0601 

1036 

25 

10.3 

i 240.1 

1186.6 

.0625 

996 

26 

11.3 

242.3 

1187.3 

.0650 

958 

27 

12.3 

244.4 

1187.8 

.0673 

926 

28 

13.3 

246.4 

1188.4 

.0696 

895 

29 

14.3 

248.4 

1189.1 

.0719 

866 

30 

15.3 

250.4 

1189.8 

.0743 

838 

31 

16.3 

252.2 

1190.4 

.0766 

813 

32 

17.3 

254.1 

1190.9 

.0789 

789 

33 

18.3 

255.9 

1191.5 

.0812 

767 

34 

19.3 

257.6 

1192.0 

.0835 

746 

35 

20.3 

259.3 

1192.5 

.0858 

726 

36 

21.3 

260.9 

1193.0 

.0881 

707 

37 

22.3 

262.6 

1193.5 

.0905 

688 

38 

23.3 

264.2 

1194.0 

.0929 

671 

39 

24.3 

265.8 

1194.5 

.0952 

655 

40 

25.3 

267.3 

1194.9 

.0974 

640 

41 

26.3 

268.7 

i 1195.4 

i .0996 

625 

42 

! 27.3 

i 270.2 

1195.8 

.1020 

611 

Appendix  I. — Continued. 

PROPERTIES  OF  SATURATED  STEAM. 


675 


Total  pressure 

per  sq.  inch, 

measured  from 

a vacuum 

Pressure  above 
the  atmosphere 

Sensible  temper- 
ature in  Fahr- 
enheit degrees. 

Total  heat  in  de- 

grees from  ze- 
ro of  Fahren- 
heit.   

Weight  of  one 

cubic  foot  of 

steam 

Relative  volume 
of  the  steam 
compared  with 
the  water  from 
which  it  was 
raised , 

Lb. 

Lb. 

Deg. 

Deg. 

Lb. 

43 

28.3 

271.6 

1196.2 

.1042 

598 

44 

29.3 

273.0 

1196.6 

.1065 

585 

45 

30.3 

274.4 

1197.1 

.1089 

572 

46 

31.3 

275.8 

1197.5 

.1111 

561 

47 

32.3 

277.1 

1197.9 

.1133 

550 

48 

33.3 

278.4 

1198.3 

.1156 

539 

49 

34.3 

279.7 

1198.7 

.1179 

529 

50 

35.3 

281.0 

1199.1 

.1202 

518 

51 

36.3 

282.3 

1199.5 

.1224 

509 

52 

37.3 

283.5 

1199.9 

.1246 

500 

53 

38.3 

284.7 

1200.3 

.1269 

491 

54 

39.3 

285.9 

1200.6 

.1291 

482 

55 

40.3 

287.1 

1201.0 

.1314 

474 

56 

41.3 

288.2 

1201.3 

.1336 

466 

57 

42.3 

289.3 

1201.7 

.1364 

458 

58 

43.3 

290.4 

1202.0 

.1380 

451 

59 

44.3 

291.6 

1202.4 

.1403 

444 

60 

45.3 

292.7 

1202.7 

.1425 

437 

61 

46.3 

293.8 

1203. 1 

.1447 

430 

62 

47.3 

294.8 

1203.4 

.1469 

424 

63 

48.3 

295.9 

1203.7 

.1493 

417 

64 

49.3 

296.9 

1204.0 

.1516 

411 

65 

50.3 

298.0 

1204.3 

.1538 

405 

66 

51.3 

299.0 

1204.6 

.1560 

399 

67 

52.3 

300.0 

1204.9 

.1583 

393 

68 

53.3 

300.9 

1205.2 

.1605 

388  I 

69 

54.3 

301.9 

1205.5 

.1627 

383  | 

70 

55.3 

302.9 

1205.8 

.1648 

318  j 

71 

56.3 

303.9 

1206.1 

.1670 

373  j 

72 

57.3 

304.8 

1206.3 

.1692 

368 

73 

58.3 

305.7 

1206.6 

.1714 

363 

74 

59.3 

306.6 

1206.9 

.1736 

359 

75 

60.3 

307.5  | 

1207.2 

.1759  i 

353 

76 

61.3 

308.4 

1207.4 

.1782 

349 

77 

62.3 

309  3 

1207.7 

.1804 

345 

78 

63.3  1 

310.2 

1208.0 

.1826 

341 

79 

64  3 

311.1 

1208.3 

.1848  1 

337 

80 

65.3 

312.0 

1208.5 

.1869 

333 

81 

66.3 

312.8 

1208.8 

.1891 

329 

82 

67.3 

313.6  | 

1209.1 

.1913 

325 

83 

68.3 

314  5 

1209.4 

.1935 

321 

84 

69.3 

315.3 

1209.6 

.1957 

318 

L 85  - 

70.3  1 

316.1 

1209.9  I 

.1980  | 

314 

676 


Appendix  I. — Continued \ 

PROPERTIES  OF  SATURATED  STEAM. 


Total  pressure 

per  sq.  inch, 

measured  from 

a vacuum 

Pressure  above 

the  atmosphere 

l 

(Sensible  temper- 

ature in  Fahr- 
enheit degrees. 

Total  heat  in  de 

grees  from  ze- 

ro of  Fahren- 
heit   

Weight  of  one  ■ 

cubic  foot  of 
steam 

Relative  volume 
of  the  steam 
compared  with 
the  water  from 
which  it  was 
raised 

Lb. 

Lb. 

Deg. 

Deg. 

Lb. 

86 

71.3 

316.9 

1210.1 

.2002 

311 

87 

72.3 

317.8 

1210.4 

.2024 

308 

88 

73.3 

318.6 

1210.6 

.2044 

305 

89 

74.3 

319.4 

1210.9 

.2067 

301 

90 

75.3 

320.2 

1211.1 

.2089 

298 

91 

76.3 

321.0 

1211.3 

.2111 

295 

92 

77.3 

321.7 

1211.5 

.2133 

292 

93 

78.3 

322.5 

1211.8 

.2155 

289 

94 

79.3 

323.3 

1212.0 

.2176 

286 

95 

80.3 

324.1 

1212.3 

.2198 

283 

96 

81.3 

324.8 

1212.5 

.2219 

281 

97 

82.3 

325.6 

1212.8 

.2241 

278 

98 

83.3 

326.3 

1213.0 

.2263 

275 

99 

84.3 

327.1 

1213.2 

.2285 

272 

100 

85.3 

327.9 

1213.4 

.2307 

270 

101 

86.3 

328.5 

1213.6 

.2329 

267 

102 

87.3 

329.1 

1213.8 

.2351 

265 

103 

88.3 

329.9 

1214.0 

.2373 

262 

104 

89.3 

330.6 

1214.2 

.2393 

260 

105 

90.3 

331.3 

1214.4 

.2414 

257 

106 

91.3 

331.9 

1214.6 

.2435 

255 

107 

92.3 

332.6 

1214.8 

.2456 

253 

108 

93.3 

333.3 

1215.0 

.2477 

251 

109 

94.3 

334.0 

1215.3 

.2499 

249 

110 

95.3 

334.6 

1215.5 

.2521 

247 

111 

96.3 

335.3 

1215.7 

.2543 

245 

112 

97.3 

336.0 

1215.9 

.2564 

243 

113 

98.3 

336.7 

1216.1 

.2586 

i 241 

114 

99.3 

337.4 

1216.3 

.2607 

239 

115 

100.3 

338.0 

1216.5 

.2628 

237 

116 

101.3 

338.6 

1216.7 

.2649 

235 

117 

102.3 

339.3 

1216.9 

.2674 

233 

118 

103.3 

339.9 

1217.1 

.2696 

231 

119 

104.3 

340.5 

1217.3 

.2738 

229 

120 

105.3 

341.1 

1217.4 

.2759 

227 

121 

106.3 

341.8 

1217.6 

.2780 

225 

122 

107.3 

342.4 

1217.8 

.2801 

224 

123 

| 108.3 

343.0 

1218.0 

.2822 

222 

124 

109.3 

343.6 

1218.2 

.2845 

221 

125 

110.3 

344.2 

1218.4 

.2867 

219 

126 

111.3 

344.8 

1218.6 

.2889 

217 

127 

112.3 

345.4 

1218.8 

.2911 

215 

1 128 

, 113.3 

346.0 

1218.9 

.2933 

214 

Appendix  I. — Continued. 


67? 


PROPERTIES  OF  SATURATED  STEAM. 


Total  pressure 

per  sq.  inch, 

measured  from 

a vacuum 

i 

Pressure  above 
the  atmosphere 

Sensible  temper- 

ature in  Fahr- 
enheit degrees. 

Total  heat  in  de- 

grees from  ze- 
ro of  Fahren- 
heit  

Weight  of  one 

cubic  foot  of 

steam 

Relative  volume 
of  the  steam 
compared  with 
the  water  from 
which  it  was 
raised 

Lb. 

129 

Lb. 

114.3 

Deg. 

346.6 

Deg. 

1219.1 

Lb. 

.2955 

212 

130 

115.3 

347.2 

1219.3 

.2977 

211 

131 

116.3 

347.8 

1219.5 

.2999 

209 

132 

117.3 

348.3 

1219.6 

.3020 

208 

133 

118.3 

348.9 

1219.8 

.3040 

206 

134 

119.3 

349.5 

1220.0 

I .3060 

205 

135 

120.3 

350.1 

1220.2 

.3080 

203 

136 

121.3 

350.6 

1220.3 

.3101 

202 

137 

122.3 

351.2 

1220.5 

.3121 

200 

138 

123.3 

351.8 

1220.7 

.3142 

199 

139 

124.3 

352.4 

1220.9 

.3162 

198 

140 

125.3 

352.9 

1221.0 

.3184 

197 

141 

126.3 

353.5 

1221.2 

.3206 

195 

142 

127.3 

354.0 

1221.4 

.3228 

194 

143 

128.3 

354.5 

1221.6 

.3250 

193 

144 

; 129.3 

355.0 

1221.7 

.3273 

192 

145 

130.3 

355.6 

1221.9 

.3294 

190 

146 

131.3 

356.1 

1222.0 

.3315 

189 

| 147 

132.3 

356.7 

1222.2 

.3336 

188 

148 

133.3 

357.2 

1222.3 

.3357 

187 

149 

1 134.3 

357.8 

1222.5 

.3377 

186 

1 150 

135.3 

358.3 

j 1222.7 

.3397 

184 

155 

140.3 

361.0 

1223.5 

.3500 

179 

160 

145.3 

363.4 

1224.2 

.3607 

174 

165 

150.3 

366.0 

1224.9 

.3714 

169 

170  - 

155.3 

368.2 

1225.7 

.3821 

164 

175 

160.3 

370.8 

1226.4 

.3928 

159 

180 

165.3 

372.9 

1227.1 

.4035 

155 

185 

170.3 

375.3 

1227.8 

.4142 

151 

190 

175.3 

377.5 

1228.5 

.4250 

148 

195 

180.3 

379.7 

1229.2 

.4357 

144 

200 

185.3 

381.7 

1229.8 

.4464 

141 

210 

195.3 

386.0 

1231.1 

.4668 

135 

220 

205.3 

389.9 

1232.3 

.4872 

129 

230 

215.3 

393.8 

1233.5 

.5072 

123 

240 

225.3 

397.5 

1234.6 

.5270 

119 

250 

235.3 

401.1 

1235.7 

.5471 

114 

260 

245.3 

404.5 

1236.8 

.5670 

110 

270 

255.3 

407.9 

1237.8 

.5871 

106 

280 

265.3 

411.2 

1238.8 

.6070 

102 

290 

275.3 

414.4 

1239.8 

.6268 

99 

300 

285.3 

417.5 

1240.7 

.6469 

96 

678 


Appendix  II. 


TABLE  OF  HYPERBOLIC  LOGARITHMS. 


Num. 

Logarithms. 

Num. 

Logarithms. 

Num. 

Logarithms. 

Num. 

Logarithms. 

1.01 

.0099 

1.46 

.3784 

1.91 

.6471 

2.36 

.8586 

1.02 

.0198 

1.47 

.3852 

1.92 

.6523 

2.37 

.8628 

1.08 

.0295 

1.48 

.3920 

1.93 

.6575 

2.38 

.8671 

1.04 

.0392 

1.49 

.3987 

1.94 

.6626 

2.39 

.8712 

1.05 

.0487 

1.50 

.4054 

1.95 

.6678 

2.40 

.8754 

1.06 

.0582 

1.51 

.4121 

1.96 

.6729 

2.41 

.8796 

1.07 

.0676 

1.52 

.4187 

1.97 

.6780 

2.42 

.8837 

1.08 

.0769 

1.53 

.4252 

1.98 

.6830 

2.43 

.8878 

1.09 

.0861 

1.54 

.4317 

1.99 

.6881 

2.44 

.8919 

1.10 

.0953 

1.55 

.4382 

2.00 

.6931 

2.45 

.8960 

1.11 

.1043 

1.56 

.4446 

2.01 

.6981 

2.46 

.9001 

1.12 

.1133 

1.57 

.4510 

2.02 

.7030 

2.47 

.9042 

1.13 

.1222 

1.58 

.4574 

2.03 

.7080 

2.48 

.9082 

1.14 

.1310 

1.59 

.4637 

2.04 

.7129 

2.49 

.9122 

1.15 

.1397 

1.60 

.4700 

2.05 

.7178 

2.50 

.9162 

1.16 

.1484 

1.61 

.4762 

2.06 

.7227 

2.51 

.9202 

1.17 

.1570 

1.62 

.4824 

2.07 

.7275 

2.52 

.9242 

1.18 

.1655 

1.63 

.4885 

2.08 

.7323 

2.53 

.9282 

1.19 

.1739 

1.64 

.4946 

2.09 

.7371 

2.54 

.9321 

1.20 

.1823 

1.65 

.5007 

2.10 

.7419 

2.55 

.9360 

1.21 

.1962 

1.66 

.5068 

2.11 

.7466 

2.56 

.9400 

1.22 

.1988 

1.67 

.5128 

2.12 

.7514 

2.57 

.9439 

1.23 

.2070 

1.68 

.5187 

2.13 

.7561 

2.58 

.9477 

1.24 

.2151 

1.69 

.5247 

2.14 

.7608 

2.59 

.9516 

1.25 

.2231 

1.70 

.5306 

2.15 

.7654 

2.60 

.9555 

1.26 

.2341 

1.71 

.5364 

2.16 

.7701 

2.61 

.9593 

1.27 

.2390 

1.72 

.5423 

2.17 

.7747 

2.62 

.9631 

1.28 

.2468 

1.73 

.5481 

2.18 

.7793 

2.63 

.9669 

1.29 

.2546 

1.74 

.5538 

2.19 

.7839 

2.64 

.9707 

1.30 

.2623 

1.75 

.5596 

2.20 

.7884 

2.65 

.9745 

1.31 

.2700 

1.76 

.5653 

2.21 

.7929 

2.66 

.9783 

1.32 

.2776 

1.77 

.5709 

2.22 

.7975 

2.67 

.9820 

1.33 

.2851 

1.78 

.5766 

2.23 

.8021 

2.68 

.9858 

1.34 

.2926 

1.79 

.5822 

2.24 

.8064 

2.69 

.9895 

1.35 

.3001 

1.80 

.5877 

2.25 

.8109 

2.70 

.9932 

1.36 

.3074 

1.81 

.5933 

2 26 

.8153 

2.71 

.9969 

1.37 

.3148 

1.82 

.5988 

1 2.27 

.8197 

2.72 

1.0006 

1.38 

.3220 

1.83 

.6043 

2.28 

.8241 

2.73 

1.0043 

1.39 

.3293 

1.84 

.6097 

2.29 

.8285 

2.74 

1.0079 

1.40 

.3364 

1.85 

.6151 

2.30 

.8329 

2.75 

1.0116 

1.41 

.3435 

1.86 

.6205 

2.31 

.8372 

2.76 

1.0152 

1.42 

.3506 

1.87 

.6259 

2.32 

.8415 

2.77 

1.0188 

1.43 

.3576 

1.88 

.6312 

2.33 

.8458  ! 

2.78 

1.0224 

1.44 

.3646 

1 89 

.6365 

2.34 

.8501 

1 2.79 

1.0260 

1.45 

.3715 

1.90 

.6418 

2.35 

.8544  ! 

1 2.80 

1.0296 

Appendix  II. — Continued. 


679 


TABLE  OF  HYPERBOLIC  LOGARITHMS. 


Num. 

Logarithms,  j 

Num. 

Logarithms. 

Num. 

Logarithms. 

Num. 

Logarithms. 

2.81 

i 

1.0331 

3.26 

1.1817 

3.71 

1.3110 

4.16 

1.4255 

2.82 

1.0367 

3.27 

1.1847 

3.72 

1.3137 

4.17 

1.4279 

2.88 

1.0402 

3.28 

1.1878 

3.73 

1.3164 

4.18 

1.4303 

2.84 

1.0438 

3.29 

1.1908 

3.74 

1.3190 

4.19 

1.4327 

2.85 

1.0473 

3.30 

1.1939 

3.75 

1.3217 

4.20 

1.4350 

2.86 

1.0508 

3.31 

1.1969 

3.76 

1.3244 

4.21 

1.4374 

2.87 

1.0543 

3.32 

1.1999 

3.77 

1.3271 

4.22 

1.4398 

2.88 

1.0577 

3.33 

1.2029 

3.78 

1.3297 

4.23 

1.4422 

2.89 

1.0612 

3.34 

1.2059 

3.79 

1.3323 

4.24 

1.4445 

2.90 

1.0647 

3.35 

1.2089 

3.80 

1.3350 

4.25 

1.4469 

2.91 

1.0681 

3.36 

1.2119 

3.81 

1.3376 

4.26 

1.4492 

2 92 

1.0715 

3.37 

1.2149 

3.82 

1.3402 

4.27 

1.4516 

2.93 

1.0750 

3 38 

1.2178 

3.83 

1.3428 

4.28 

1.4539 

2.94 

1.0784 

3.39 

1.2208 

3.84 

1.3454 

4.29 

1 4562 

2.95 

1.0818 

3.40 

1.2237 

3.85 

1.3480 

4.30 

1.4586 

2.96 

1.0851 

3.41 

1.2267 

3.86 

1.3506 

4.31 

1.4609 

2.97 

1.0885 

3.42 

1.2296 

3.87 

1.3532 

4.32 

1.4632 

2.98 

1.0919 

3 43 

1.2325 

3.88 

1.3558 

4.33 

1.4655 

2.99 

1.0952 

3.44 

1.2354 

3.89 

1.3584 

4.34 

1.4678 

3.00 

1.0986 

3.45 

1.2387 

3.90 

1.3609 

4.35 

1.4701 

| 3.01 

1.1019 

3.46 

1.2412 

3.91 

1 3635 

4.36 

1.4724 

1 3.02 

1.1052 

3.47 

1.2441 

3.92 

1.3660 

4.37 

1.4747 

! 3.03 

1.1085 

3.48 

1.2470 

3.93 

1.3686 

4.38 

1.4778 

| 3.04 

1.1118 

3.49 

1.2499 

3.94 

1.3711 

4.39 

1.4793 

1 3.05 

1.1151 

3.50 

1.2527 

3.95 

1.3737 

4.40 

1.4816 

3.06 

1.1184 

3.51 

1.2556 

3.96 

1.3726 

4.41 

1.4838 

j 3.07 

1.1216 

3.52 

1.2584 

3.97 

1.3787 

4.42 

1.4838 

3.08 

1.1249 

3.53 

1.2612 

3.98 

1.3812 

4.43 

1.4883 

3.09 

1.1281 

3.54 

1.2641 

3.99 

1.3857 

4.44 

1.4906 

: 3.10 

1.1314 

3.55 

1.2669 

4.00 

1.3862 

4.45 

1.4929 

3.11 

1.1346 

3.56 

1.2697 

4.01 

1.3887 

4.46 

1.4914 

3.12 

1.1378 

3.57 

1.2725 

4.02 

1.3912 

4.47 

1.4973 

3.13 

| 1.1410 

3.58 

1.2753 

4.03 

1.3937 

4.48 

1.4996 

3.14 

1.1442 

3.59 

1.2781 

4.04 

1.3962 

4.49 

1.5018 

3.15 

1.1474 

3.60 

1.2809 

4.05 

1.3987 

4.50 

1.5040 

3.16 

1.1505 

3.61 

1.2837 

4.06 

1.4011 

4.51 

1.5062 

3.17 

1.1537 

3.62 

1.2864 

4.07 

1.4036 

4.52 

1.5085 

3.18 

I 1.1568 

3.63 

1.2892 

4.08 

1.4060 

4.53 

1.5107 

3.19 

1.1600 

; 3.64 

1.2919 

4.09 

1.4085 

4.54 

1.5129 

3.20 

i 1.1631 

3.65 

1.2947 

4.10 

1.4109 

4.55 

1.5151 

3.21 

1.1662 

3.66 

1.2974 

4.11 

1.4134 

1 4.56 

1.5173 

3.22 

1.1693 

3.67 

1.3001 

4.12 

1.4158 

4.57 

1 .5195 

3.23 

1.1724 

3.68 

1.3029 

4 13 

1.4182  1 

1 4.58 

1.5216 

3.24 

1.1755  | 

3.69 

1 3056 

4.14 

| 1.4206 

4.59 

1.5238 

3.25 

1.1786  | 

1 3.70 

1.3083 

I 4.15 

| 1.4231 

4.60 

1.5260 

680  Appendix  II. — Continued. 


TABLE  OF  HYPERBOLIC  LOGARITHMS. 


Num. 

Logarithms. 

Num. 

Logarithms. 

Num. 

Logarithms. 

Num. 

Logarithms,  j 

4.61 

1.5282 

5.06 

1.6213 

5.51 

1.7065 

5.96 

1.7850 

4.62 

1.5303 

5.07 

1.6233 

5.52 

1.7083 

5.97 

1.7867 

4.63 

1.5325 

5.08 

1.6253 

5.53 

1.7101 

5.98 

1.7884 

4.64 

1.5347 

5.09 

1.6272 

5.54 

1.7119 

5.99 

1.7900 

4.65 

1.5368 

5.10 

1.6292 

5.55  1 

1.7137 

6.00 

1.7917 

4.66 

1.5390 

5.11 

1.6311 

5.56 

1.7155 

6.01 

1.7934 

4.67 

1.5411 

5.12 

1.6331 

5.57 

1.7173 

6.02 

1.7950 

4.68 

1.5432 

5.13 

1.6351 

5.58 

1.7191 

6.03 

1.7967 

4.69 

1.5454 

5.14 

1.6370 

5.59  | 

1.7209 

6.04 

1.7984 

4.70 

1.5475 

5.15 

1.6389 

5.60 

1.7227 

6.05 

1.8000 

4.71 

1.5496 

5.16 

1.6409 

5.61  1 

1.7245 

6.06 

1.8017 

| 4.72 

1.5518 

5.17 

1.6428 

5.62  j 

1.7263 

6.07 

1.8033 

i 4.73 

1.5539 

5.18 

1.6448 

5.63 

1.7281 

6.08 

1.8050 

4.74 

1.5560 

5.19 

1.6463 

5.64 

1.7298 

6.09 

1.8066 

4.75 

1.5581 

5.20 

1.6486 

5.65 

1.7316 

6.10 

1.8082 

4.76 

1.5602 

5.21 

1.6505 

5.66 

1.7334 

6.11 

1.8099 

4.77 

1.5623 

5.22 

1.6524 

5.67 

1.7351 

6.12 

1.8115 

4.78 

1.5644 

5.23 

1.6544 

5.68 

1.7369 

6.13 

1.8131 

| 4.79 

1.5665 

5.24 

1.6563 

5.69 

1.7387 

6.14 

1.8148 

1 4.80 

1.5686  1 

5.25 

1.6582 

5.70 

1.7404 

6.15 

1.8164 

4 81 

1.5706  i 

5.26 

1.6601 

5.71 

1.7422 

6.16 

1.8180 

4.82 

1.5727  | 

5.27 

1.6620 

5.72 

1.7439 

6.17 

1.8196 

4.83 

1.5748 

5.28 

1.6639 

5.73 

1.7457 

6.18 

1.8213 

1 4.84 

1.5769  i 

5.29 

1.6658 

5.74 

1.7474 

6.19 

1.8229 

4.85 

1.5789  i 

5.30 

1.6677 

5.75 

1.7491 

6.20 

1.8245 

i 4.86 

1.5810 

5.31 

1.6695 

5.76 

1.7509 

6.21 

1.8261 

4.87 

1.5830 

5.32 

1.6714 

5.77 

1.7526 

6.22 

1.8277 

| 4.88 

1.5851 

5.33 

1.6733 

5.78 

1.7544 

6.23 

1 1.8293 

1 4.89 

1.5870 

5.34 

1.6752 

5.79 

1.7561 

6.24 

i 1.8309 

4.90 

1.5892 

5.35 

1.6770 

5.80 

1.7578 

6.25 

1.8325 

4.91 

1.5912 

5.36 

1.6789 

5.81 

1.7595 

6.26 

1.8341 

4.92 

1.5933 

5.37 

1.6808 

5.82 

1.7613 

6.27 

1.8357 

4.93 

1.5953 

5.38 

1.6826 

5.83 

1.7630 

6.28 

1.8373 

4.94 

1.5973 

5.39 

1.6845 

5.84 

1.7647 

6.29 

1.8389 

4.95 

1.5993 

5.40 

1.6863 

5.85 

1.7664 

6.30 

1.8405 

4.96 

1.6014 

5.41 

1.6882 

5.86 

1.7681 

6.31 

1.8421 

4.97 

1.6034 

5.42 

1.6900 

5.87 

1.7698 

6.32 

1.8437 

! 4.98 

1.6054  1 

5.43 

1.6919 

5.88 

1.7715 

6.33 

1.8453 

4.99 

1 6074  j 

5.44 

1.6937 

5.89 

1.7732 

6.34 

1.8468 

5.00 

1.6094  1 

5.45 

1.6956 

5.90 

1.7749 

6.35 

1.8484 

5.01 

1.6114  ; 

5.46 

1.6974 

5.91 

1.7766 

6.36 

1.8500 

; 5.02 

1.6134 

5.47 

1 6992 

5.92 

1.7783 

6.37 

1.8515 

i 5.03 

1.6154  i 

5.48 

1.7011 

5.93 

1.7800 

6.38 

1.8531 

i 5 04 

1.6174 

i 5.49 

1.7029 

5.94 

1.7817  ! 

6.39 

1.8547 

5.05 

1.6193  1 

! 5.50 

1.7047 

5.95 

1.7833 

6.40 

1.8562 

INDEX 


Abr — Air 

Abrasion  of  flanges,  401. 

Absolute  pressure,  28,  30,  51,  53,  56. 

“ in  cylinders,  64. 

Accelerated  motion,  2. 

Acceleration  of  falling  bodies,  3. 

“ piston,  106,  110,  111. 

“ reciprocating  parts,  369. 

“ “ speed,  375. 

Accidental  application  of  brakes,  525. 

Accidents  and  injuries  to  persons,  663-673. 

“ from  being  on  track,  664. 

“ to  locomotives,  598,  643-662. 

Action  of  pistons,  cranks,  and  driving-wheels, 
357-369. 

Actual  energy,  35,  38. 

Adams.  W.,  260. 

Adams\  “vortex”  blast-pipe,  260-262. 

Addition,  xi. 

Adhesion,  116. 

“ and  traction,  370-375. 

“ amount  needed,  121. 

“ “ of,  371. 

“ of  locomotive,  diagram  of,  370. 

“ “ wheels,  112,  540,  541,  542. 

Adhesive  weight,  124,  544,  545. 

Admission,  equalization  of,  100,  341. 

“ line,  329. 

of  eccentrics,  346,  349. 

“ “ steam,  78,  81,  91,293  , 295,  317, 

318. 

“ steam,  how  affected  by  throw 
period  of,  94,  314. 

“ pre,  of  steam,  295. 

“ width  of  opening  for,  341. 

Air,  admission  of,  573. 

“ “ “ above  fire,  561,  564. 

“ “ “ at  furnace  door,  574. 

“ “ “ to  fire-box,  562. 

“ amount  to  be  admitted  to  fire,  562,  631 . 

“ “ of  admitted  to  fire-box,  562. 

“ and  steam,  forces  of,  24. 

“ brake,  accidental  application  of,  525. 

“ “ application  of  from  inside  of  car, 

529. 

“ “ and  release  of , 526, 528. 

“ “ automatic,  483,  484,  485. 

“ freight  train,  operation 
of,  532,  533. 

“ “ care  of,  531. 


Air— Alu 

Air-brake,  care  and  use  of,  521-532. 

“ “ inspection  of,  523. 

“ “ release  of,  527, 528. 

“ “ “ “ on  car,  530. 

“ “ straight,  483. 

“ “ use  of  in  danger,  526. 

“ “ Westinghouse,  482-520.  Plate  VI. 

“ chamber,  218. 

“ cold,  admission  of  to  fire-box,  562. 

“ composition  of,  551. 

“ compressed,  484,  485,  504. 

“ compression  of,  53. 

“ essential  for  combustion,  259. 

“ exhaust  of,  534. 

“ gauges,  522,  528. 

“ importance  of  pure,  639. 

“ insufficient  supply  of,  561. 

“ “ “ “ effect  on  combus- 

tion, 555. 

“ leakage  of,  523,  525,  528. 

“ mixed  with  gas,  557. 

“ must  be  mixed  with  gas,  559. 

“ need  of  for  health,  640. 

“ pressure,  excess  of,  522,  525,  527,  528. 

“ “ gauge,  524, 526. 

“ “ of,  24,  25,  53,  54,  528. 

“ “ reduction  of , 526. 

“ proportion  above  and  below  the  fire,  568. 
“ pump,  482,  484,  493,  497,  498,  521,  5*4,  528. 
“ “ care  of,  521,  531,  532. 

“ required  for  perfect  combustion,  566, 567. 
“ requisite  supply  of,  561. 

“ reservoir,  482,  483. 

“ “ auxiliary,  484, 485,  486, 488,  489, 

493,  503,  504,  506,  507,  509,  510, 
512,513,523,  524,  525,  526. 

“ “ main,  484, 487, 488, 489, 494,  495, 

497,  504,  522,  524,  527,  532. 

“ supply,  control  of,  583. 

“ regulation  of,  569. 

“ “ subdivision  of,  564, 565. 

“ too  much  of  in  fire-box,  561. 

“ variation  of  pressure  of,  25. 

“ volume  of,  30,  53,  54. 

“ waste  of,  526. 

“ weight  of,  24. 

Algebraic  symbols,  use  of,  xi. 

Allen  valve,  319,  320. 

Alumina,  473. 


682 


Index. 


Alu — Att 

Alumina,  precipitation  of,  472. 

American  cars,  resistance  of,  586,  590. 

44  locomotives,  122. 

“ “ construction  of,  122. 

“ “ dimensions  of,  122. 

44  “ engravings  of,  148, 

150.  Plates  III,  IV, 
and  V. 

“ “ plan  of,  402.  Plate  V. 

11  44  weight  of,  122. 

44  “ 44  and  dimen- 

sions of,  149,  151. 
Ammonia,  water  of,  472,  473. 

Analysis  of  water,  472. 

Angle,  deflection  and  tangential,  590,  591. 

“ of  connecting-rod,  101. 

“ “ thread,  453. 

“ “ wheels  to  rails,  401. 

Angles  of  deflection  of  curves,  table  of,  592, 
593. 

Angular  advance,  343,  344,  345. 

44  motion  of  crank-pin,  300. 

Angularity  of  connecting-rod,  98, 100, 105, 107, 
109,  111. 

“ “ “ “ effect  of,  367. 

Annealing  steel  plates,  192. 

Anthracite  coal,  173,  580. 

44  44  chimney  for,  214. 

44  “ combustion  of,  581. 

44  “ firing  with,  633. 

“ “ grate  for,  179, 252. 

“ “ 44  and  fire-box,  580,  581. 

Apple,  views  of,  xiv. 

Application  of  brakes,  485,  488,  497,  526,  528. 

“ “ accidental,  525. 

“ “ force  of,  513,  514. 

“ “ for  ordinary  stops,  525. 

“ from  inside  of  car,  502, 
529. 

“ of  vacuum  brake,  536. 

Apron,  473. 

Aqua-fortis,  553. 

Area  of  pistons,  rule  for,  542. 

“ “ ports,  349. 

Argand  burner,  435. 

Arithmetical  calculations,  xi. 

Army  and  navy  department,  452. 

Arterial  bleeding,  45. 

Arteries,  position  of,  666,  667. 

Ascent,  resistance  due  to,  587. 

Ashcroft  Manufacturing  Co.,  247. 

“ steam  gauge,  246. 

Ashes,  584. 

“ removal  of,  617. 

“ should  be  cleaned  out  of  smoke-box, 
602. 

Ash-pan,  117,  168,  179,  253. 

“ care  of,  603,  631. 

“ cleaning  of,  617. 

“ examination  of,  633. 

Atmosphere,  pressure  of,  25. 

Atmospheric  line,  53,  55,  60,  62,  329. 

44  pressure,  29,  53,  55,  534. 

Atoms,  combination  of,  551. 

“ excited  into  activity,  554. 

Attraction  of  gravitation,  3,  106. 


Aut — Bil 

Automatic  action  of  brakes,  485,  486. 

“ air-brake,  483,  484,  485.  Plate  VI. 
“ brake,  504. 

“ 44  cylinders,  pressure  in,  517. 

“ freight  train  brake,  operation  of, 
532,  533. 

Auxiliary  air  reservoir,  484,  485,  486,  488,  489, 
493,  503,  504,  506,  507, 509,  510, 512, 513,  523, 
524,  525,  526,  530. 

Average  pressure,  67. 

44  “ in  cylinder,  63. 

Axle  112. 

“ boxes,  338,  355. 

“ “ arrangement  of,  416. 

“ “ of  tender,  465,  466,  467. 

“ broken  or  bent,  657. 

“ driving,  broken,  655. 

44  how  held,  116. 

“ pressure  on,  373-377. 

“ truck  broken,  655. 

Axles,  care  of,  610. 

“ heating  of,  35. 

44  parallel,  395. 

Babbitts  metal,  270,  275,  280,  604. 

Back  gear,  286,  341. 

4 1 pressure,  70, 71 , 72,  260,  329,  333,  835,  338, 
340,  341,  547. 

“ 11  line,  329. 

“ “ loss  from,  75, 

44  44  on  piston,  220, 340. 

Balance  on  wheels,  377. 

44  out  of,  376. 

Balanced  valve,  350,  351. 

Baldwin  Locomotive  Works,  113,  211. 

“ “ 44  locomotives  by, 

134, 160, 162, 164, 

Ball  joint,  257,  260. 

Balloon,  25. 

Band,  on  spring,  418,  420. 

Bandage,  use  of,  666. 

Banked,  fire,  618. 

Banking  fire,  650. 

44  system  of  firing,  632. 

Bars,  bearing,  252. 

“ grate,  252. 

Bath,  substitute  for,  640. 

Bathing,  importance  of,  637,  640. 
Bauschmger’s  indicator  experiments,  322. 
Beams,  brake,  467,  482,  484. 

Bearing-bars,  252. 

Bearings,  frictional,  proportions  of,  442. 

Bed  castings,  263. 

Bed-plate,  263. 

Bedroom,  ventilation  of,  640. 

Bell,  435. 

“ crank,  255-256. 

“ should  be  rung,  618,  619. 

Belpaire,  fire-box,  177. 

44  44  engravings  of,  178. 

Bennett,  Peter  D.,  tests  of  iron  and  steel  bars, 
192. 

44  Big-end”  of  connecting-rod,  277. 
Billiard-ball,  18. 

44  engraving  of,  10. 


Index. 


683 


Bis— Boi 

Bissell,  Louis,  430. 

“ truck,  125,  430,  431,  432. 

“ “ adjustment  of  to  track,  433. 

“ “ advantages  of,  434. 

Bituminous  coal,  burning  of,  562. 

“ composition  of,  554. 

“ effect  of  on  fire,  553. 

“ grate  bars  for,  252. 

“ rules  for  firing,  633. 

Blast.  171,  546. 

area  of,  338. 
contraction  of,  333. 
effect  of,  546. 
in  chimney,  337. 
influence  of  on  draft,  581. 
orifice,  171,  260. 
pipe,  260-262. 

should  be  in  centre  of  chimney,  603. 
Blasts,  effect  of  many,  549. 

Bleed,  530. 

Bleeding,  528. 

“ brakes,  524,  527. 

“ danger  of,  665. 

“ stopping  of,  666,  667. 

Blisters,  treatment  of,  671. 

Blocks,  brake,  467. 

“ link,  356. 

“ Blow,”  significance  of,  605. 

Blower,  249. 

“ cock,  249. 

“ use  of,  619,  637,  649. 

“ valves,  care  of,  604. 

“ Blowing  through,”  packing,  604. 

Blow-off,  cocks,  249. 

” danger  of  opening,  623. 

“ opening  of,  634. 

Boat,  15. 

movement  of,  11, 13. 

Boiler,  112. 

and  wheels,  reiation  of  size  of,  549. 
attachments,  216. 

“ care  of,  604. 
calculation  of  steam  on,  184. 
capacity,  584. 

“ of,  584. 
cleaning  of,  634,  635. 
defects  in,  how  discovered,  601. 
engraving  of,  169,  170. 
examination  of,  649. 
expansion  of,  415,  617. 
explosions,  cause  of,  647. 

prevention  of,  648. 
feeding  of,  620,  621. 
foaming  of,  621,  622. 
head,  leak  of,  600. 
large  advantages  of,  547. 
leaks  in,  600. 
plate,  testing  of,  189. 

” strength  of,  187. 
plates,  how  fastened,  191. 

“ punching  and  injuring  of,  192. 
priming  of,  621,  622. 
production  of  largest  quantity  of 
steam,  by,  631. 

relation  between  size  and  action  of,  j 
547. 


Boi — Bra 

Boilers,  168. 

“ advantage  of  large,  625. 

“ cannot  be  too  large,  546,  549. 

“ danger  of  no  water,  617. 

“ expansion  and  contraction  of,  188. 

“ feeding  uniformly,  625. 

“ insufficient  strength,  cause  of  explo- 
sions, 647. 

“ materials  of,  187. 

” old,  test  of,  600. 

“ operation  of,  546. 

“ proportions  of,  546. 

“ should  be  kept  clean,  601. 

“ size  of,  545,  546. 

“ steel,  specifications  of,  190. 

“ strain  on,  184. 

“ strains  on  from  expansion,  617. 

“ strength  of,  72. 

“ testing  of,  598. 

“ too  full,  622. 

” “ small,  547. 

“ vertical,  124, 126. 

“ washing  of,  601,  602. 

“ waste  of,  117. 

“ weakness  of,  599. 

“ weight  and  dimensions  of,  546. 

Boiler-seam,  breaking  of,  193. 

u calculation  of,  strength  of,  193. 
“ comparison  of,  strength  of,  198. 
“ proportions,  of,  199. 

“ “ strength  of,  204. 

“ “ table  of  single-riveted,  195. 

“ “ welted,  206. 

Boiling,  26. 

“ point,  26,  27. 

Boiler,  A.  P.,  477. 

Bolsters,  swing,  430. 

Bolt-heads  and  nuts,  standard  sizes  of,  454, 
460. 

“ shape  of,  459,  460. 

Bolts  and  nuts,  451-460. 

“ strength  of,  453. 

“ table  of,  454. 

Bones,  broken,  treatment  of,  668,  669. 

Books,  reading  of,  642. 

Boxes,  axle,  355. 

“ driving,  arrangement  of,  416. 

“ journal,  412. 

“ oil  on  journal  or  axle,  465,  466,  467. 

“ wear  of,  416. 

Boyle,  Robert,  law  of,  30. 

Boyle’s  law,  54. 

Braces,  broken,  599. 

“ design  and  construction  of,  178. 

“ in  boiler,  defects  in,  601. 

“ strain  on,  618. 

Brake,  accidental  application  of,  525. 

" air,  care  of,  531. 

“ “ release  of,  527,  528. 

“ “ ” and  use  of,  521-532. 

” “ use  of  in  danger,  526. 

“ application  and  release  of,  526,  528. 

for  ordinary  stops,  525. 

“ of,  485,  488,  497. 

“ from  inside  of  car,  502, 
529. 


684 


Index. 


Bra— Bra 

Brake,  automatic,  504. 

“ “ air,  484, 485. 

“ “ freight  train  operation  of, 

532,  533. 

“ beam  levers,  515,  519. 

“ beams,  467,  482,  484. 

“ blocks,  467. 

“ “ heating  of,  35. 

“ cock,  523. 

“ cord,  529. 

“ cylinder,  483,  484,  485,  486,  488,  489,  497, 
501,  503,  504,  506,  508,  509,  510,  512,  513. 
515,  524,  530. 

“ cylinders,  care  of,  531. 

“ pressure  in,  517. 

“ defects  in,  524. 

“ driving-wheel,  503,  504. 

“ Eames’  vacuum,  534-539. 

“ freight  car,  523. 

“ “ “ 505, 506,  and  plate  opp.  505. 

" gear,  adjustment  of,  521. 

hangers,  467. 

hose,  483,  484, 485,  488,  502,  522,  523,  528, 
529  531 

levers,  467,  483,  484,  514,  515. 

“ arrangement  of,  514,  515,  518, 

519. 

“ calculation  of,  517. 

“ “ live,”  519. 

“ rules  for  calculating,  519,  520. 

“ shaft,  468. 

‘ ‘ shoe,  for  vacuum  brake,  538,  539. 

Brakeman,  524,  532. 

Brake-pipe  cock,  530,  531. 

“ pipes,  leakage  of,  504. 

“ “ 482, 483, 484. 485, 486, 488,  489,  493, 

494,  495, 496;  497,  502,  503,  504,  509, 
511,  513,  523,  524,  525,  526,  527,  529, 
531. 

“ pistons,  483,  501,  513,  521,  525,  531. 

“ quick-acting,  520. 

“ shoes,  467,  482,  483,  484,  503,  536. 

“ “ pressure  of,  calculation  for  515, 

520. 

“ “ pressure  on,  485,  538. 

“ valve,  engineer’s,  484,  485,  487,  488, 
489,  490,  491,  492,  493,  495,  496,  504,  509, 
510,  521,  524,  526. 

“ Westinghouse  air,  482-520.  Plate  VI. 
“ windlass,  482,  515. 

Brakes,  continuous,  not  to  be  depended  on  in 
entering  stations,  627. 

“ continuous,  to  be  applied  gradually, 
628. 

“ “ cutting-out,”  530. 

“ driver,  use  of,  530. 

“ driving-wheel  adjustments  of,  521. 

“ force  of  application  of,  213,  514. 

“ hand,  482,  515,  523. 

“ inspection  of,  523. 

“ of  tender,  467. 

” release  of,  485,  488,  496,  497,  504,  522. 

“ “ “ on  car,  530. 

“ straight  air,  504. 

“ tender  inspection  of,  614, 

“ test  of,  524. 


Bra — Cap 

Brakes,  use  of  in  danger,  644. 

Bran,  to  prevent  leaks  in  boiler,  600. 

Brandy,  how  and  when  to  give  it,  668,  671. 
Brass  bearings,  care  of,  608. 

“ “ for  connecting-rods,  277. 

“ journal-bearing,  465,  466,  467. 

“ less  liable  to  abrasure  than  othei 
metals,  444. 

“ resistance  of  to  wear,  49. 

“ tubes,  175. 

Brasses,  48. 

“ for  connecting-rods,  277. 

Brazil  coal,  597. 

Break  joints,”  270. 

Breaking  coal,  566. 

Breathing,  how  to  stimulate,  672. 

Brick-arch,  cleaning  of,  617. 

“ engraving  of,  572. 

“ 574. 

“ section  of,  573. 

Bridges,  43,  81,  89. 

“ danger  at,  629. 

“ width  of,  349. 

Brook’s  Locomotive  Works,  locomotive  by 
140. 

Brooms,  use  of,  629. 

Brosius,  J.,  415. 

Bubbles  of  steam,  27. 

“ “ motion  of,  621. 

Buchanan’s  fire-box,  576-579. 

] Buckets,  iron,  473. 

: Bulging  of  plates,  601. 

I Bumper-timber,  414. 

Bunsen  burner,  557,  558. 

Burner,  Bunsen,  557,  558. 

Burning,  551. 

“ boiler,  623. 

“ coal,  579,  580. 

“ fuel,  adaptation  of  appliances  for. 

584. 

Burns,  treatment  of,  671. 

Burst  hose,  530. 

Bursting  of  tube,  649. 

Bushing,  47. 

Bushings,  for  connecting-rods,  277. 

Butt-joint  or  seam,  204-206. 

“ joints,  200,  206. 

‘ seam,  205. 

1 ‘ seams,  table  of  proportions,  209. 

Cab,  118. 

Cages,  216. 

Caking  coal,  568. 

Calculation  of  velocity  of  falling  body,  6. 
Caliper  limit  gauges,  457,  458. 

Calipers,  453. 

“ use  of,  606. 

Canadian  Pacific  Railway,  236. 

Candle,  555,  557,  558. 

Cannon-ball,  2. 

“ “ engraving  of,  7,  8. 

“ balls,  movement  of,  6,  7. 

Canvas  hose,  461. 

Capacity  of  boilers,  546,  549. 

“ “ cylinders,  544. 

‘k  “ “ measure  of,  544. 


Index. 


685 


Cap — Che 

Capacity  of  locomotive,  limitation  of,  547. 

Car,  axle,  heating  of,  35. 

“ coal  consumed  per  mile,  596. 

“ detached  from  train,  531. 

“ steam,  dimensions  and  engraving  of,  166. 
“ wrecking  or  tool,  647. 

Carbon,  551,  552,  554,  555,  556,  557,  558,  560, 
561,  566,  568,  570,  580,  581. 

Carbonic  acid,  552. 

“ “ gas,  560. 

“ anhydride,  560. 

“ dioxide,  560,  561,  562,  566,  568,  581. 

“ oxide,  560,  561,  562,  568,  581. 

Card,  indicator,  59. 

Cards,  indicator,  engravings  of,  61. 

Care  and  inspection  of  locomotives,  598-616. 

“ “ use  of  air-brake,  521-532. 

“ of  brake-cylinders,  531. 

Carriage  wheel,  108. 

Carrying  wheels,  use  of,  392. 

Cars,  breaking  loose,  626. 

“ resistance  of,  585-594. 

“ tables  of  resistance  of,  588,  589. 

Cast-iron  truck  wheels,  engraving  of,  410. 

Catechitical  form,  iv. 

Caulker’s  thumb-tool,  183. 

Caulking  Connery’s  system  of,  211. 

“ danger  of,  599. 

“ edges,  210. 

“ flues,  600. 

“ of  boiler  seams,  210. 

“ tubes,  need  of,  601. 

Caution,  need  of,  638. 

Centre  bearing,  467. 

“ of  gravity  of  counterweight,  389,  391. 
“ pin,  392,  393. 

“ “ of  truck,  433. 

“ plate,  428,  467. 

“ “ not  in  centre,  611. 

“ plates,  lubrication  of,  614. 

Centres,  wheel,  113. 

Centrifugal  force,  108. 

“ “ diagram  of,  378,  380. 

“ “ “ “ effect  of,  387. 

“ “ of  counterweight,  377,  386. 

“ “engine,  401. 

“ “ “ reciprocating  parts,  357. 

“ “ “ revolving  weights,  380. 

“ “ rule  for  calculating, 108, 109. 

Centripetal  force,  108. 

Chain  riveting,  200. 

Chains,  check,  467. 

“ “ and  safety,  439. 

Change  of  form,  indicative  of  weakness  of 
boiler,  599. 

Channel-bars,  461. 

Check-chains,  439,  467. 

“ valve,  218,  224. 

“ “ engraving  of,  219. 

“ “ for  vacuum  brake,  538. 

“ valves,  care  of,  604,  613,  614. 

“ “ closed,  617. 

“ “ failure  of,  650. 

“ “ of  brake  hose,  483. 

Chemical  analysis  of  water,  472. 
combination,  554. 


Che — Coa 

Chemical  combustion  attending  phenomena, 
551. 

“ composition  of  fuel,  584. 

“ elements,  551. 

“ equivalents,  552. 

“ Society  of  Paris,  568,  570. 
Chemistry,  551. 

Chestnuts,  how  to  keep  hot,  33. 

Chilling,  definition  of,  410. 

Chimney,  117,  118,  168,  171. 

“ glass,  555,  556. 

“ influence  of,  582. 

Chimneys,  construction  and  height  of,  215. 

“ engravings  of,  213,  214. 

Chloride  of  magnesium,  473. 

Chute,  coal,  473,  474,  477. 

Cinders,  179,  212,  570. 

“ arrest  of,  118. 

“ collection  of,  582,  584. 

“ removal  of,  617. 

“ should  be  cleaned  out  of  smoke-box, 
602. 

Circulation,  imperfect,  621,  622.  % 

“ of  water,  181. 

Circumferential  seams,  207. 

Cistern,  463,  464. 

Cities,  railroads  in,  123,  125. 

Citizen’s  Sanitary  Association,  639. 

Civil  engineers,  590. 

Clamp,  414. 

Clamps,  expansion,  414. 

Clark,  D.  K.,  391. 

Clark’s  railway  machinery,  423. 

Cleaning,  cost  of.  595. 

“ engine,  598,  634. 

Cleanliness,  need  of  for  health,  639. 
Clearance,  49,  75. 

“ diagram  showing  effect  of,  76. 

“ inside,  97. 

“ loss  from,  71. 

“ of  piston,  317. 

“ space,  75,  77,  97,  321,  322,  323,  335, 

340. 

‘ ‘ space,  contents  of,  332. 

“ spaces,  steam  in,  340. 

Clinker,  568,  584,  632. 

Clinkers,  removal  of,  617. 

Coal,  560,  561,  562,  563,  566,  568,  579. 

“ amount  consumed  per  mile,  596. 

“ anthracite,  580. 

“ bituminous,  burning  of,  562. 

composition  of,  554. 

“ effect  of  on  fire,  553. 

“ Brazil,  597. 

“ breaking  of,  631. 

“ burning  of,  579,  580. 

“ caking,  568 
" chute,  473,  474,  477. 

combustion  of,  553-562. 

“ consumed  by  locomotive  per  mile,  596. 

“ per  car  per  mile,  596. 

“ consumption,  economy  of,  579,  580. 

“ distribution  of  on  grate,  631. 

“ effect  of  fresh  on  fire,  553,  554. 

“ evaporation  of  water  fcy,  172. 

“ gas,  557,  580. 


686 


Index. 


Coa — Com 

Coal  gas,  flame  of,  560. 

“ “ perfect  combustion  of,  558. 

“ loss  or  waste  of,  37. 

“ quantity  burned  per  hour,  172. 

“ should  be  broken,  566. 

“ supply  of,  473. 

“ thickness  of  on  grate,  563,  632. 

Coaling  station,  474. 

Cock,  blow-off,  249. 

“ blower.  249. 

“ brake,  523. 

“ “ pipe,  530,  531. 

“ cylinder  oil,  268. 

“ feed,  220,  621. 

“ four- way,  487,  489,  504,  523. 

“ “ 530. 

“ frost,  220. 

“ pet,  220. 

“ release,  530. 

“ stop,  523,  529. 

“ surface,  623. 

“ three-way,  506. 

Cocks,  cylinder,  268. 

“ gauge  or  try,  236,  237. 

“ heater,  opening  of,  622. 

“ “ use  of,  628. 

Co-efficient  of  friction,  441,  443. 

Coke,  560,  562,  568. 

combustion  of,  560. 

“ consumption  of,  561. 

Colburn’s  Locomotive  Engineering,  172, 176. 

Cold  air,  admission  of  to  fire-box,  562,  563. 

“ effect  of  in  setting  valves,  356. 

“ water,  leakage  of,  599. 

“ “ test,  598. 

“ weather,  662. 

“ “ precaution  in,  636. 

“ “ precautions  to  be  taken  in,  628. 

“ “ running  in,  628. 

Collapse,  669,  671. 

“ of  tube,  649. 

Collar,  on  axle,  465,  466. 

Collision,  prevention  of,  643,  644. 

Collisions,  tail  end,  644. 

Color-blindness,  627. 

Combination  of  elements,  effect  of,  553. 

Combining-tube,  224. 

Combustion,  551, 558, 560,  561,  562,  563,  564,  566, 
567,  574,  579,  584. 
activity  of,  546. 
appliances  for  improving,  584. 
enough  air  essential  for,  559. 
essentials  of  good,  559. 

“ of  coal,  553-562,  564. 

‘‘  “ and  prevention  of  smoke, 

553. 

“ “ fuel,  117,  118, 168. 

“ gas,  explanation  of,  554. 

“ heat  of,  560. 

how  influenced  by  smoke-box, 
581. 

improvement  of,  584. 

“ intensity  of,  569. 

“ in  tubes,  565. 

“ perfect,  563,  568. 

“ products  of,  559. 


Com— Con 

Combustion,  rate  of,  172,  562. 

“ rapidity  of,  631. 

results  of,  559. 

“ second,  581. 

“ total  heat  of,  560,  569. 

Components,  13. 

Composition  of  motion,  14,  15,  16. 

Compound  engines,  77. 

locomotive,  vi,  126. 

“ system,  advantages  of,  126. 

Compress,  use  of,  663. 

Compressed-air,  484,  485,  504, 

Compression,  16,  94,  97.  321,  322,  323,  330,  331. 
advantages  of,  77,  339. 
after  exhaust  closure,  340. 

“ curve,  330. 

effect  of,  384. 

“ excessive,  339. 

good  effects  of,  338. 
in  cylinder,  335. 

“ necessary,  340. 

of  steam,  77,  317. 

“ air,  diagram  of,  52. 

“ point  of,  295,  330. 

“ strain,  187. 

Concussions  of  cars,  533. 

Condensation,  62. 

in  cylinders,  71,  77,  336,  340. 

“ of  steam,  31. 

Condenser,  for  locomotives,  124. 

Conducting  power  of  substances,  32. 

“ properties  of  substances,  37. 

i Conduction  of  heat,  32,  75. 

“ “ loss  by,  37. 

I Conductor’s-valve,  524,  528,  529. 

“ “ 502. 

Cone,  213. 

“ of  wheel,  396-405. 

Coned  wheels,  diagram  of,  396,  397. 

“ “ “ action  of,  398,  399. 

Conical  form  of  wheel,  influence  of,  400-405. 

“ wheels,  396-406. 

Conicity  of  wheels,  imaginary  advantages  of, 
i 400. 

Connecting-rod,  action  of,  98,  100. 

“ “ angularity  of,  100,  105,  107, 

111. 

“ “ broken, 654. 

“ effect  of  on  velocity  of  piston, 
103. 

“ “ influence  of,  357. 

“ “ weight  of,  385. 

“ rods,  40,  47,  48,  87,  90,  263,  273, 
276,  280. 

“ “ action  of  on  stability,  391. 

“ “ care  of,  607,  608. 

“ “ effect  of  angularity  of,  367. 

“ “ thrust  of,  376. 

[ Connection  of  tender  to  engine,  465. 
Connery’s  system  of  caulking,  211. 
Consolidation  locomotive,  123,  275. 

“ dimensions  and  weight 
of,  157. 

“ “ engraving  of,  156. 

Contents,  ix.  [entering  stations,  627. 

Continuous  brakes,  not  to  be  depended  on  in 


Index. 


687 


Con — Cra 

Continuous  brakes,  to  be  applied  gradually, 
628. 

Contraction  of  boilers,  188. 

Convection  of  heat,  32,  573. 

“ “ from  boiler,  212. 

Convertibility  of  heat  into  work,  37. 
Convey-pipes,  accidents  to,  602. 

Cooke  Locomotive  and  Machine  Works,  loco- 
motive by,  128. 

“ J.  P.,  Jr.,  551,  552,  555. 

Cooking,  640. 

Copper  ferrule,  engraving  of,  182. 
ferrules,  184. 

“ fire-box  plates.  174. 

Cord,  brake,  529. 

Corroding,  effect  of  water,  472. 

Corrosion,  dangerous,  601. 

“ internal  in  boiler,  601 . 

of  boilers  due  to  tension  on  plates, 
208. 

“ “ old  boilers.  600. 

Corrosive  substances  in  water,  472,  473. 

“ water,  601. 

Cost  of  operating,  595. 

“ “ locomotives,  595-597. 

Cotter,  49,  459. 

Cotton,  conducting  power  of,  33. 

“ waste,  465. 

Counterbalance,  see  also  counterweight. 

weights,1 409. 

Counterforce,  21,  22,  23. 

Countersunk  bolt-head,  459,  460. 
Counterweight,  effect  of,  377. 
Counterweights,  409. 

centre  of  gravity  of,  389, 391. 
“ centrifugal  force  of,  386. 

“ diagram  of  action  of,  377, 382. 

“ location  and  construction  of, 

379 

‘ ‘ rules  for  calculating,  389-391 . 

Coupling,  528. 

“ breakage  of,  661. 

“ hooks,  523. 

“ hose,  483,  484,  485,  488,  502,  522, 
523,  528,  629,  531. 

“ of  engine  and  tender,  619. 

“ pin,  465. 

“ rod,  weight  of,  385. 

“ “ 116,  276. 

“ rods,  care  of,  607,  608. 

“ “ reason  for  taking  down  both, 

654. 

“ screw,  463. 

Couplings,  hose,  frozen,  532. 

Covering  strip,  200,  206. 

Covers,  for  cylinder  heads,  268. 

Cow-catcher,  118,  414,  437. 

“ use  of,  629. 

Cracked  plates  in  boiler,  601. 

“ “ fire-box,  600. 

Cracking  of  fire-box  plates.  618. 

Crane,  16 ; engraving  of,  17  ; strain  on,  16. 
Cranes,  473. 

Crank  40,  41,  46,  47,  48,  85,  87,  89,  91,  98,  112, 
113,  281,  356. 

“ axles,  127. 


Cra — Cur 

Crank,  action  of,  98. 

“ and  piston,  diagram  of,  86. 

“ diagram  of  movement  of,  99,  102,  107. 
“ effect  of  pressure  on,  338. 

“ pin,  48,  49,  87,  93,  98,  99,  110,  113,  273, 
280,  281,  386. 

“ “ angular  motion  of,  300. 

“ “ boss,  379. 

“ “ “ weight  of,  385- 

“ “ broken,  654. 

“ “ care  of,  607,  608. 

“ centrifugal  force  at,  380. 

“ “ diagram  of  centrifugal  force  at, 

387. 

“ “ “ “ centrifugal  force  on, 

378. 

“ “ “ “ pressure  on,  358. 

“ “ effect  of  position  on,  375, 

“ “ pressure  on,  357. 

“ “ rotative  effect  on,  diagram  of,  361, 

365,  368. 

“ “ unbalanced  weight  on,  377. 

“ “ velocity  of,  104. 

“ “ weight  of,  385. 

* ‘ pins,  construction  of,  408,  409. 

“ “ engraving  of,  409. 

“ “ how  lubricated,  441. 

“ “ effect  of  position  of,  375. 

“ “ movement  of,  107. 

“ pressure  on,  65. 

“ rotative  effect  on,  360-369. 

Cranks,  action  of,  357-369. 

Crosby  indicator,  325,  326. 

“ Steam  Gauge  & Valve  Co.,  326. 
Cross-head,  48,  85,  91,  100,  101,  263,  280. 

“ “ broken,  654. 

“ “ guides,  how  lubricated,  444. 

“ “ pin,  87,  98,  99. 

“ “ slides,  care  of,  607. 

“ “ velocity  of,  104. 

“ “ weight  of,  385. 

“ section,  xv. 

Crossing,  626,  628. 

“ collisions  at,  645. 

“ railroads,  crossing  of,  645. 

“ “ rule  for,  645. 

Crow-bars,  use  of,  653. 

Crown-bars,  176. 

“ “ braces  for.  178. 

“ “ removal  of,  602. 

“ plate,  overheating,  621. 

“ sheet,  174. 

“ “ exposure  off,  626,  650. 

“ “ staying  of,  17  . 

“ sheets,  slope  of,  178. 

Crushed  person,  treatment  of,  671. 

Crushing  of  plates,  193. 

“ “ rails,  540,  541. 

“ “ rivets,  193. 

Culverts,  danger  at,  629. 

Curved  track,  392, 

Curves,  121. 

“ action  of  locomotives  on,  395. 

“ “ “ wheels  on,  395. 

“ degree  of,  590,  591.  [398. 

“ diagram  of  action  of  wheels  on,  394, 


688 


Index. 


Cur—  Cyl 


Dam— Dia 


Curves,  difference  in  length  of  inner  and 
outer  rail  of,  395. 

“ effect  of  on  resistance  of  trains,  590. 

“ expansion,  54. 

“ motion,  89,  92,  93. 

“ engravings  of,  95,  96. 

“ on  long  grade,  547. 

‘ ‘ radii  and  deflection  angles  of,  592,  593. 
“ railroad,  method  of  laying  out, 590, 591. 
“ running  through,  624. 

“ sharp,  626. 

“ shortest,  540. 

Cushion  of  steam,  82,  94,  317,  322. 

“ “ effect  of,  384. 

Cut-off,  65,  70,  71. 

“ how  influenced  by  throw  of  eccentric, 
344. 


“ of  steam,  51. 

44  point  of,  313.  314,  329,  340. 

Cutting  out  brakes,  522,  530. 

Cylinder,  29,  40,  48,  53,  263,  280. 

“ and  diagram  of  compression  and 
expansion  of  air,  52. 

“ “ piston,  engraving  of,  36.  [57. 

“ “ steam  indicater,  engraving  of, 

brake,  483.  484,  485,  486,  488,  489,  497, 
501,  503,  504.  506,  508,  509,  510,  512, 
513,  515,  524,  530. 
breaking  of,  621. 
capacity,  544. 

“ measure  of,  544. 
casing,  268, 
cocks,  268. 

“ opening  of,  618,  635, 

“ use  of,  645. 
comparison  of  sizes  of,  543. 
cover,  40. 
head,  40,  46,  263. 

“ covers,  268. 

“ broken,  653. 
increasing  size  of,  73. 
lagging,  268. 
lengthened,  72. 
lengthening  of,  76. 
levers,  515,  519. 

“ calculation  of,  518. 
lugs,  414. 

vacuum  brake,  534. 
water  in,  521. 

Cylinders,  advantage  of  short  stroke,  550. 
brake,  care  of,  531. 

“ pressure  in,  517. 
broken,  652. 
care  of,  605. 

diameter  and  stroke  of,  545. 

“ of,  rule  for,  542. 
inside,  126. 
inspection  of,  604. 
location  of,  113. 
oil-cock,  268. 
outside,  126. 
protection  of,  268,  336. 
see  also  brake-cylinder, 
size  of,  122,  541,  543. 
use  of  two,  49,  112. 

Cylindrical  nuts,  458,  459. 


Damp  clothes,  danger  from,  640. 

Damper,  for  ash-pan,  253. 

“ on  ash-pan,  use  of,  629. 

Dampers,  117,  168. 

44  for  ash-pan,  179. 

Dampness,  injurious  effects  of  on  health,  639. 
Danger,  how  it  should  be  encountered,  638. 

44  imminent,  487. 

“ of  being  on  railroad  track,  664. 

44  use  of  air-brake  in,  526. 

Dangers,  of  locomotive  engineers,  637. 
Dead-grates,  565. 

14  plates,  569. 

“ points,  41,  49,  91,  98,  101,  108,  112,  273, 
282,  338,  361,  364,  381,  382,  655. 

“ stop,  at  crossings,  626. 

Debauch,  color-blindness  after,  627. 

Decapod  locomotive,  123. 

engraving  of,  160. 
dimensions  and  weight 
of,  161. 

Defects  in  boiler,  how  discovered,  601. 

“ “ brake,  524. 

“ “ fire-box, 601. 

Deflecting  plate  over  furnace  door,  575. 

“ plates,  inspection  of,  602, 
Deflection  angle,  590,  591. 

44  angles,  table  of,  592,  593. 

44  of  springs,  rule  for  calculating, 
423. 

Deflector,  for  furnace  door,  574,  575. 

44  in  smoke-box,  583,  584. 

Deflectors,  212,  213,  574,  582. 

Degree  of  curve,  590,  591. 

Delivery-tube,  224. 

Denver  & Rio  Grande  Railroad,  544. 

Descent  of  grades,  506. 

Diagonal,  16. 

?4  pitch  of  rivets,  202. 

Diagram,  indicator,  62,  63. 

“ of  action  of  coned  wheels,  396,  397, 
398,  399. 

“ “ action  of  counterweights,  382. 

44  “ 44  “ equalizing  levers,  426. 

44  44  “ 44  two  pistons,  383. 

4 4 44  4 4 4 4 wheels,  393. 

4 4 44  4 4 44  4 4 on  curves,  394. 

4 4 4 4 adhesion  of  locomotive,  370. 

44  “ centrifugal  force,  380. 

44  44  44  44  on  crank-pin, 

378. 

4 4 “ composition  of  forces,  engraving 

of,  16. 

44  “ effect  of  centrifugal  force,  387. 

44  “ engine,  44,  45. 

44  “ falling  bodies,  4. 

44  “ motion  of  valve,  42. 

44  “ movement  of  boat,  11,  13. 

44  44  44  4 4 crank,  107. 

4 4 4 4 44  4 4 piston  and  crank, 99. 

4 4 4 4 piston  and  crank.  86. 

4 4 4 4 pressure  on  crank-pin,  358. 

44  “ rotative  effect  on  crank-pin,  361, 

365,  368. 

“ tractive  power,  374. 

44  “ valve  motion,  297,  298. 


Index. 


689 


Dia— Dri 


Dri — Ecc 


Diagram  of  velocity  of  piston,  105. 

showing  momentum  of  reciprocating 
parts,  110. 

“ “ movement  of  crank  and 

piston,  102. 

Diagrams  of  arrangement  of  tubes,  180. 

“ “ eccentric,  88. 

“ “ link-motion,  287, 288, 290, 291, 292. 

“ “ movement  of  link,  316. 

“ showing  advantages  of  expan- 

sion, 66. 

“ “ strain  on  boilers,  185, 

Diameter  of  cylinders,  rule  for,  542. 
Diameters  of  screws,  456,  457. 

Diamond  stack,  213. 

Diaphragm  of  steam-gauge,  243. 

“ vacuum  brake,  534,  536,  538. 

“ vessel,  534,  536,  538. 

Die,  Schule  des  Locomotivfiihrers,  415. 

Dies,  192,  457. 

Different  kinds  of  locomotives,  121. 

Dilution  of  gas,  567. 

Diminishing  pressure  of  steam,  51. 

Directions  for  use  of  Nathan’s  sight  feed 
lubricator,  449,  450. 

Disc,  538. 

Dissipation,  injurious  effects  of,  638. 

Distance  in  which  train  can  be  stopped,  520. 

“ signals,  645. 

Distribution  of  steam,  315,  340. 

“ “ weight,  540. 

“ “ ‘‘  of  engine,  425,  426, 

427. 

Disturbing  forces,  internal,  376-391. 

Division,  xii. 

“ sign  of,  xii. 

Dome,  211. 

“ cover,  removal  of,  601. 

“ location  of,  212. 

“ steam  drawn  from,  622. 

Domes,  use  of  two,  622. 

Door,  drop,  252. 

“ furnace,  117,  249. 

“ “ and  fire-box,  574, 575, 576. 

Dotted  lines,  use  of,  xv. 

Doty,  Dr.  Alvah  H.,  669,  671,  673. 
Double-header,  527,  529,  530. 

“ poppet  throttle-valve,  254-256. 

“ riveted  seam,  proportions  of,  202, 203. 

“ “ seams,  202. 

“ threaded  screw,  451. 

“ welted  seam,  206. 

Draft,  171. 

“ amount  of,  546. 

“ dependent  on,  etc.,  581. 

“ effect  on  of  many  blasts,  549. 

“ through  fire,  333. 

“ violent,  effect  of,  547. 

Drain-cup,  487,  489,  532. 

Draw-bar,  118,  465. 

Drawbridge,  accidents  at,  645. 

approaching,  626. 

Drawing  fire,  652. 

Drilled  rivet  holes,  198. 

Drilling  locomotives,  121. 

“ rivet  holes,  192, 


Drink,  strong,  injury  of,  637. 

Drinking  too  much,  639. 

Drip,  237. 

“ cup,  503. 

Driving-axle  boxes,  arrangement  of,  416. 

“ “ broken, 655. 

“ axles,  care  of,  612. 

“ boxes,  care  of,  610. 

“ engraving  of,  413. 

“ “ wear  of,  611. 

“ wheel  brake,  503,  504. 

“ “ “ vacuum,  537,  538. 

“ brakes,  adjustment  of,  521. 

“ “ broken, 655. 

“ “ use  of,  530. 

“ wheels,  113. 

“ action  of,  357-369,  404. 

“ adhesion  of,  friction  of,  load 
on,  weight  on,  370. 

“ adhesive  weight  of,  540,  541. 

“ back  or  trailing,  116. 

“ care  of,  610. 

“ construction  of,  406. 

“ effect  of  size  of,  549. 

“ “ engraving,  406. 

“ how  fastened  to  axles,  408. 

“ “ number  needed,  116. 

“ “ position  of,  123. 

“ “ size  of,  541, 543. 

“ “ slip  of,  370, 619. 

“ “ use  of,  392. 

“ “ weight  on,  121, 543. 

Drilling  boiler  plates,  195. 

Drop-door,  252. 

“ properly  fastened,  617. 

Drowning,  treatment  for,  672. 

Drum,  mud,  249. 

Drunken  engineer,  637. 

Dry-pipe,  212. 

Dry  steam,  211. 

“ color  of,  622. 

“ effect  of,  624. 

Ductility  of  boiler  plates,  188. 

Dudgeon’s  roller  expander,  183. 

Dudley,  C.  B.,  473. 

Duplicate  parts  to  be  carried,  615. 

Dust-guard,  465,  466. 

Duties  of  engineers,  640. 


Eames’  vacuum  brake,  534-539. 

“ ejector  for,  535. 

Eating,  640. 

“ too  much,  639. 

Ebullition,  26,  211. 

convulsive,  621. 

Eccentric,  42,  82,  84,  85,  87,  89,  90,  92,  93,  116, 
281,  356. 

“ broken,  659. 

“ diagrams  of,  88. 

“ engraving  of,  42,  82. 

“ rod,  43,  85,  116,  281,  284,  356. 

“ broken,  659. 

“ change  of  length  of,  659. 

“ engraving  of,  42. 

“ set  of,  116., 

“ slipped,  657  659. 


690 


Index. 


Ecc — Equ 

Eccentric  strap,  42,  48. 

“ “ engraving  of,  42. 

“ straps,  care  of,  608,  609. 

Eccentrics,  effect  of  throw  of,  341. 

‘ ‘ keyed  to  axles,  356. 

proportions  of,  346. 

“ throw-off,  T8,  87. 

Economy  of  boiler,  173. 

“ “ coal  consumption,  579,  580. 

“ “ expansion,  65,  70,  71. 

“ “ running  engine,  520. 

“ 44  using  steam  expansively,  68. 

Education,  need  of,  641. 

Effective  pressure,  28,  30,  31,  63. 

“ in  cylinders,  334. 
Efficiency  of  steam,  68. 

Ejector,  534,  535,  536,  538. 

Elastic  limit,  638. 

“ “ of  material,  600. 

“ strength  of  spring,  420. 

Elasticity,  limit  of,  188,  420. 

11  of  spring,  420,  421. 

“ springs,  rule  for  calculating,  423 
Electric  spark,  554, 

Elementary  substances,  551 . 

combination  of,  552. 
Elements,  effect  of  combination  of,  553. 

“ of  Machine  Design,  202. 

Elevated  railroads  of  New  York,  539. 
Elevator  and  billiard-ball,  engraving  of,  10. 

“ Emergencies”  and  how  to  treat  them,  663, 

666. 

Emergency,  497,  529. 

“ stop,  521. 

End-play  of  journals,  need  of,  610. 

“ “ wheels,  399. 

Energy,  34. 

“ convertible  into  heat,  35. 

“ waste  of,  65. 

Engine,  care  of  at  end  of  run,  134. 

44  detached  from  train,  531. 

“ diagrams  of,  44,  45. 

“ house,  care  and  inspection  of  locomo- 
tives in,  598-616. 

“ leading,  529. 

“ steam,  40.  See  also  locomotive. 

“ towing  of,  653,  655. 

Engineer,  524,  525,  528,  529,  530,  531,  532,  533. 
Engineering,  507. 

Engineer’s  brake-valve,  484,  485,  487,  488,  489, 
490,  491,  492,  493,  495, 
496,  504,  509,  510,  521, 
524,  526. 

“ “ reservoir,  494,  495, 

496. 

“ cost  of  service  of,  595. 

“ responsibility  and  qualifications 

of,  637-642. 

“ valve,  628. 

Engines,  application  of  power  of,  112. 

“ two  to  one  train,  527,  529. 

England,  126. 

English  coal,  596. 

4 engine,  coal  consumed  per  mile,  596. 
Equal  to,  sign  of,  xii. 

Equalizer,  425. 


Equ — Exp 

Equalizers,  care  of,  612. 

Equalizing-lever  or  beam,  424,  425. 

44  levers,  432,  433. 

44  broken,  655. 

44  diagram  of  action  of,  426. 
44  “ of  truck,  428. 

Equivalent  of  heat,  36. 

European  cars,  resistance  of,  586,  590. 
Evaporation,  26. 

44  heat  of,  554. 

latent  heat  of,  38,  39. 
of  water,  26. 

“ per  pound  of  coal,  172. 

Excess  of  air  pressure,  489,  493,  525,  527,  528. 
Exercise,  need  of  for  health,  639. 

Exhaust,  81. 

44  cavity,  41,  81. 

44  of  valve,  97. 

44  closure,  point  of,  330, 340. 

44  curve,  93. 

44  edge,  of  valve,  308. 

44  line,  329,  337. 

44  nozzle,  171,  260,  583. 

44  nozzles,  care  of,  603. 

44  contraction  of,  333,  547. 

“ 44  size  of,  631. 

44  of  air,  534. 

4 4 4 4 steam,  78,  82,  91,  97,  313,  314. 

44  orifices,  583. 

44  passage,  263. 

44  passages,  friction  in,  340. 

44  pipes,  259. 

44  accidents  to,  602. 

44  “ care  of,  603. 

44  port,  41,  46,  51,  82,  89,  93,  94,  263. 

44  gradual  opening  of,  340. 

44  width  of,  349. 

44  rapidity  of,  340. 

44  steam,  81,  171. 

44  44  effect  of,  546. 

44  44  escape  of,  124. 

44  variable,  260. 

44  width  of  opening  for,  341. 

Exhibition  stops,  527. 

Expander,  tube,  use  of,  600. 

Expansion,  advantages  of,  70. 

44  amount  useful,  72. 

44  clamps,  414. 

44  curve,  54,  55,  56,  62,  329,  340. 

14  “ how  to  draw  it,  55,  56. 

curves,  defects  of,  336. 

44  effect  of  on  action  of  valve-gear, 
356. 

44  high  degrees  of,  71. 

44  of  air,  diagram  of,  52. 

44  4 4 boilers,  188,  415. 

44  “ steam,  29,  36,  55,  317. 

44  “ 44  advantages  of,  65, 620. 

44  “ “ economy  of,  68. 

44  “ “ effect  of,  369. 

4 4 44  water  and  tubes,  617,  518. 

44  pressure  after,  30. 

4 4 44  during,  340. 

44  “ of  steam  during,  31. 

44  rate  of,  74. 

44  ratio  of,  64. 


Index. 


691 


Exp— Fir 

Expansion,  theoretical  economy  of,  70,  71. 
Expansive  action,  82. 

“ “ of  steam,  50. 

“ force  of  steam,  40. 

Expenses,  locomotive,  proportion  of.  596. 
Expiration,  artificial,  673. 

Experiments,  locomotive,  597. 

Explode,  attempt  to,  599. 

Explosion,  danger  of,  72,  621. 

Explosions,  boiler,  cause  of,  647. 

“ “ prevention  of,  648. 

Extended  smoke-boxes,  212. 

“ “ “ effect  of,  584. 

“ “ box,  on  front-end,  582,  583. 

Fahrenheit,  scale,  note  to,  36. 

Falling  body,  3. 

“ “ calculation  of  velocity  of,  6. 

“ bodies,  acceleration  of,  3. 

“ “ diagram  of,  4. 

“ “ velocity  of,  4,  5,  106. 

Fatigue,  effects  of,  638. 

Feed-cock,  220,  621. 

“ pipe,  216. 

“ water,  increasing  amount  of,  624. 

“ “ point  of  admission  of,  571. 

Feeding  boiler,  620,  621, 

“ boilers  uniformly,  625. 

Felt,  212. 

“ for  covering  cylinders,  268. 

Ferrule,  copper,  engraving,  of,  182. 

“ inside  for  tubes,  184. 

Fibre  of  boiler  plate,  187. 

Filling  funnel,  461. 

Final  pressure,  31. 

Fire-banked,  618. 

“ banking  of,  650. 

“ blown  out  of  furnace-door,  602. 

“ box,  117,  168 

“ “ Belpaire,  engraving  of,  118. 

“ “ Buchanan’s,  576-579. 

“ “ construction  of,  173. 

“ “ defect  in,  601, 

“ “ door,  574, 575, 576  See  furnace-door. 

“ “ examination  of,  600. 

“ “ for  anthracite  coal,  580,  581. 

“ “ ordinary  form  of,  573. 

“ “ plain,  573. 

“ “ plates,  strain  on,  618. 

“ “ position  of,  116. 

“ “ section  of,  572,  573,  575. 

“ “ size  of,  546 

“ “ steel,  specifications  of,  190. 

“ “ strain  on,  618. 

“ “ temperature  in,  559,  570. 

“ “ with  radial  stays,  engraving  of, 

177. 

“ brick,  574. 

“ “ arches,  574. 

“ danger  of,  602. 

“ “ “ starting  without  water,  617. 

“ draft  through,  333. 

“ drawing  of,  652. 

“ engine  hose,  463. 

“ feeding  of,  563,  631. 

“ how  to  draw  it,  650. 


Fir — For 

Fire  light,  561. 

“ starting  of,  600,  617. 

“ stimulation  of,  546. 

“ thickness  of,  562,  563. 

I Firemen,  cost  of  service  of,  595. 

. “ instruction  to,  641. 

“ knowledge  of,  580. 

“ must  be  guided  by  experience,  631, 

632. 

“ rules  for,  533. 

Firing,  598. 

“ a locomotive,  630,  631 . 

“ “ banking  system  ” of,  632. 

“ “ spreading  system  ” of,  632. 

“ with  anthracite  coal,  633. 

First  law  of  motion,  1,  2. 

Fixed  gases,  54. 

Flame,  556,  557. 

“ structure  of,  557. 

Flange  and  tread,  shape  of,  410. 

“ broken,  655. 

“ friction,  400,  401,  404,  405. 

“ of  wheel,  action  of,  395. 

Flanges  of  wheels,  position  of,  399. 

“ strain  on,  624. 

“ wear  of,  610. 

“ Flat”  tires,  405. 

Flexible  connection  of  truck  to  locomotive,  395. 
Floating  levers,  515,  519. 

Flues,  117,  168. 

“ arrangement  of,  179,  180. 

“ bursting  or  collapse  of,  649. 

“ cleaning  of,  635. 

“ defective,  600. 

“ leaky,  600. 

“ number  of  in  boiler,  117. 

“ size  of,  173. 

Fluted  connecting-rod,  277. 

Flutter  of  gauge-cocks,  623. 

Fly-wheel,  41. 

Foam,  found  on  surface  of  water,  622. 
Foaming  of  boiler,  621,  622. 

“ prevention  of,  623,  624. 

Fogs,  danger  in,  629. 

Follower-bolts,  270. 

“ Follower  bound”  piston  packing,  605. 
Follower-plate,  270,  605,  606.  ' 

Food,  637. 

Foot-board,  352. 

“ “ effect  of  weight  on,  438. 

“ “ or  foot-plate,  437, 438. 

“ pound,  34. 

“ “ calculation  of,  34. 

“ pounds  of  work  done,  74. 

Force,  1. 

“ acting  on  moving  body,  9. 

“ and  motion,  1. 

“ centrifugal,  108. 

“ centripetal,  108,  109. 

“ exertion  of,  3. 

“ magnitude  of,  12,  15. 

” of  application  of  brakes,  513,  514. 

“ “ steam,  40. 

“ pump,  598. 

“ represented  by  a line,  engraving  of, 


692 


Index. 


For— Fri 

Force  required  to  slip  wheels,  370. 

Forces  acting  on  lever,  20. 

“ internal  disturbing,  376-391. 

“ of  air  and  steam,  24. 

“ resolution  of,  10,  14. 

Form,  change  of,  indicative  of  weakness  of 
boiler,  599. 

Forney  locomotive,  for  N.  Y.  Elevated  R.R., 
“ “ dimensions  and  weight 

of,  139. 

“ “ for  N.  Y.  Elevated  R.R., 

engraving  of,  138. 

“ “ for  suburban  traffic,  di- 

mensions and  weight  of, 
137. 

“ “ for  surburban  traffic,  en- 

graving of,  136. 

“ pony  locomotive,  dimensions  and 

weight  of,  135. 

“ “ “ engraving  of,  134. 

Forward-gear,  286,  341. 

Foundation  of  turn-tables,  480. 

Four-way  cock,  487,  489,  504,  523,  530. 
Four-wheeled  locomotives,  121. 

“ switching  locomotive,  dimen- 

sions and  weight  of,  129. 

“ switching  locomotive,  engrav- 

ing of,  128. 

Fractures  in  boiler,  600. 

Frame  legs,  412. 

“ of  truck,  428. 

Frames,  112,  113,  116. 

“ broken,  657. 

“ construction  of,  412. 

“ engraving  of,  413. 

“ fastening  of,  414. 

“ of  tender  trucks,  465, 

“ protection  of,  416. 

Franklin  Institute,  452. 

Freezing  of  pumps,  220,  221. 

“ “ water  in  locomotives,  635. 

“ “ “ pumps,  etc,  628. 

Freight  car  brake,  523. 

“ “ “ 505,  506,  and  plate  oppo- 

site 505. 

“ locomotives,  121. 

“ train  brake,  automatic  operation  of, 

532,  533. 

“ trains,  difficulty  of  operating  brakes 
on,  507. 

French  Spring  Co.,  420. 

Fresh  air,  need  of,  639. 

Friction  and  lubrication,  440-450. 

“ co-efficient  of,  441. 

“ definition  of,  440. 

“ energy  required  to  overcome,  442. 

“ flange,  400,  401. 

“ in  exhaust  passages,  340. 

“ law  of,  443. 

“ of  brake-blocks,  513,  514. 

“ “ brakes,  482. 

“ “ driving-wheels,  370. 

“ “ steam,  340. 

“ “ wheels,  112. 

Frictional  bearings,  proportions  of,  442. 

“ resistance  of  locomotive,  34. 


Fro— Gib 

Frost-bite,  treatment  of,  671. 

“ cock, 220. 

Frozen  hose  couplings,  532. 

Fuel,  118,  559,  560,  561,  567,  568,  584. 

adaptation  of  appliances  for  burning, 

chemical  composition  of  584. 

“ combustion  of,  117,  118. 

“ cost  of,  595. 

“ poor  quality  of,  584. 

“ regulation  of  supply  of,  563. 

“ supply  of,  461. 

“ thickness  of  on  grate,  632. 

“ unburned,  570. 

“ value  of  different  kinds,  584. 

“ waste  of,  570. 

Fulcrum  of  driving-wheel,  379,  384. 

“ “ lever,  19. 

“ “ wheel  and  axle,  373-375. 

Full-gear,  293. 

“ forward,  286. 

Funnel,  filling,  461. 

Furnace-door,  117,  168,  249,  574,  575,  576,  577, 
578,  579. 

admission  of  air  at,  574. 
double,  576. 

English,  576. 
opening  of,  562,  622. 

“ openings  in,  632- 

Fusible-plugs,  239,  240." 

Garbage,  removal  of  640. 

Gas  burner,  555,  558. 

“ coal,  perfect  combustion  of,  558. 

“ combustion,  of,  554. 

“ evolution  of  from  coal,  553. 

“ light,  556,  559. 

“ combustion  of,  554,  555. 

“ mixed  with  air,  557. 

“ must  be  mixed  with  air,  559. 

“ repulsion  of  particles  of,  29. 

Gases,  expansion  of,  54. 

“ imperfect  combination  of,  547. 

“ in  tubes,  temperature  of,  571. 

“ mixing  of,  569. 

“ of  coal,  effect  of  on  health,  637. 

‘ ‘ pressure  of,  55. 

“ temperature  of  escaping,  571. 

“ volume  of,  55. 

Gasification,  heat  of,  38,  554. 

Gauge,  air  pressure,  485,  524,  526. 

“ cocks,  236. 

“ “ care  of,  604. 

“ for  screw-threads,  455,  456. 

“ glass,  breaking  of,  239. 

“ pressure  for  vacuum  brake,  538. 

“ steam,  243-247. 

“ water  236-238. 

Gauges,  air,  522,  528. 

“ limit.  457,  458. 

Generation  of  steam,  171. 

“ “in  boiler,  600. 

“ “ “ glass  tube,  27. 

“ “ rapidity  of,  584. 

Gib,  49. 

Gibs  in  cross-head,  275,  607. 


Index. 


693 


Gid — Gui 


Gui— Hig 


Giddings,  C.  M.,  350. 

Gland,  47. 

“ of  stuffing-box,  607. 

Glass-gauge,  236-238. 

“ “ care  of,  604. 

“ “ breaking  of,  239. 

“ tube,  generation  of  steam  in,  27. 

“ Going  lame,”  609. 

Gong,  signal,  435. 

Governor,  pump,  500,  524. 

Grade,  547. 

Grades,  descent  of,  506. 

“ effect  of  on  water  in  boiler,  625. 

“ heavy,  526,  527,  530,  572. 

“ “ train  on,  631. 

“ long,  533,  547. 

“ maximum,  597. 

“ precautions  on,  625. 

“ resistance  on,  586,  587. 

“ • “ “ rule  for,  587. 

“ running  down,  626. 

“ steep,  529. 

“ “ working  on,  626. 

“ steepest,  540. 

“ tables  of  resistance  on,  588,  589. 

Gradient,  rate  of,  587. 

Graduating-valve,  488,  509. 

Grant  Locomotive  Works,  locomotives  by, 
132,  150,  154. 

“ pony  locomotive,  dimensions  and 
weight  of, 133. 

“ “ “ engraving  of,  132. 

Graphical  representation  of  motion,  12. 

Grate,  117,  168,  250,  252. 

“ bars,  252. 

“ “ melting  of,  633. 

“ engraving  of,  170. 

“ enlargement  of,  569. 

“ for  anthracite  coal,  580,  581. 

“ rocking,  252. 

Grates,  care  of,  603,  631,  635. 

“ cleaning  of,  617. 

“ condition  of,  617. 

“ construction  of,  179. 

“ examination  of,  633. 

“ shaking,  252. 

“ size  of,  172,  546. 

“ thickness  of  fire  on,  562,  563. 

“ water,  252,  580,  581. 

Gravitation,  8,  9. 

“ attraction  of,  3,  106. 

Gravity,  resistance  due  to,  587. 

Grease  in  boiler,  621. 

“ removal  of,  635. 

Grindstone,  revolving,  108. 

Groove,  air,  501. 

“ for  air,  488. 

“ leakage,  525. 

Grooving  of  boiler,  601. 

Guide-bars,  48,  274,  276. 

“ “ care  of,  607. 

“ blocks,  275. 

“ yoke,  274. 

“ “ attachment  of,  415. 

Guides,  273. 

“ bent,  605. 


Guides,  inspection  of,  604. 
Gummy  matter  in  netting,  603. 
Gusset  stays,  engravings  of,  179. 


Half-gear,  289,  293. 

“ throw  of  valve,  282. 

Hammer,  inspection  with,  599. 

“ test  of  stay-bolts  with,  601. 
Hammering,  heating  by.  35. 

Hancock  inspirator,  230,  231. 

Hand  brakes,  482,  515,  523. 

“ holes,  249. 

“ “ opening  of,  643. 

“ rails,  437. 

Hanger  of  link,  286,  299. 

“ “ “ adjustment  of  length  of, 

356. 


Hangers,  brake,  467. 

for  springs,  416,  424. 

Head-light,  118,  435,  558. 

**  “ care  of,  615,  628. 

Heads,  cylinder,  263. 

Health,  need  of,  641. 

of  engineers,  637, 
preservation  of,  639. 

Heat,  amount  transmitted  to  water,  547. 
another  form  of  energy,  37. 
convection  of,  573. 
convertible  into  energy,  35. 
effect  of  on  cylinders,  etc.,  72. 
equivalent  of,  36. 
escape  of  up  chimney,  572. 
latent,  554. 

loss  by  conduction  and  radiation,  37. 

“ of,  32. 

mechanical  equivalent  of,  34. 
of  combustion,  560. 

“ evaporation,  554. 

“ gasification,  38  , 554. 

“ steam,  relation  of  to  pressure  and 
volume,  56. 

radiation  and  convection  of,  212. 

“ of,  570. 

required  to  convert  water  to  steam,  58, 
“ “ raise  temperature  of  water, 

36. 


resulting  from  chemical  combination, 
551. 


“ total  of  combustion,  560,  569. 

“ “ “ steam,  39. 

“ transmission  of,  561. 

“ units  of,  68,  69. 

“ waste  of,  570-573. 

Heater-cocks,  opening  of,  622. 

“ “ use  of,  628,  636. 

Heating  of  journals,  610. 

“ surface,  172. 

“ “ amount  of,  546. 

“ Helper,”  629,  630. 

Hemispherical  bolt-head,  459,  460. 

Hemp,  47. 

Hexagonal  bolt-heads  and  nuts,  458,  459,  460. 

High  expansion,  not  economical,  77. 
pressure,  advantages  of,  65. 

“ and  expansion,  67. 

•*  “ steam,  expansion  of,  71. 


694 


Index. 


Hig — Ind 


Ind — Jou 


High  speed,  97. 

“ “ of  piston,  317,  318. 

“ temperature,  effect  of  on  cylinders,  72. 
Hinkley  Locomotive  Co.,  locomotive  by,  148, 
152. 

Hodge  brake,  515,  516,  519. 

Holmes,  Geo.  V.,  Ill,  336,  340. 

Hood,  for  furnace  door,  574,  575. 

“ or  strainer,  463. 

Hook-headed  bolt,  460. 

Hooks,  coupling,  523. 

Horizontal  section,  xv. 

Horse,  15. 

“ railroads,  124. 

Hose,  461,  463. 

“ brake,  483,  484,  485,  488,  502,  522,  523, 
528,  529,  531. 

“ burst,  530. 

“ couplings,  483,  502,  522,  531. 

“ frozen,  532. 

“ fire-engine,  463. 

“ pipe,  use  of,  634. 

“ uncoupling  of,  636. 

Howe,  Dr.,  663,  666. 

Hubs,  boring  of,  408. 

Hudson  double-ender  locomotive,  dimensions 
and  weight 
of,  147. 

“ “ “ engraving 

of,  146. 

Hudson,  Wm.  S.,  126,  432. 

Hydraulic  press,  408. 

“ pressure,  test  of  boilers,  599,  600. 
Hydrogen,  551,  552,  554,  555,  556,  557,  558,  559, 
566,  570,  580. 

Hyperbolic  curve,  62,  332,  333,  335. 

“ logarithms,  64. 

Hyponitrous  acid,  553. 


Ice,  how  to  keep  cold,  33. 

“ on  rails,  371. 

“ use  of,  668. 

Igniting  temperature,  554,  555,  559  , 560,  564, 
565,  574. 

Ignition,  554. 

Illuminating  oil,  cost  of,  595. 

Incrustating  substances,  472. 

Incrustation,  prevention  of,  601,  602. 

“ removal  of,  634. 

should  be  cleaned  out  of  boilers, 
601. 


India-rubber  diaphragm,  534,  536. 
Indiana  coal,  597. 

Indicator,  59,  323. 

cards,  engravings  of,  61. 
Crosby,  323,  324. 
diagram,  engraving  of,  73. 

“ form  of,  331. 
diagrams,  62,  63,  72,  327,  340. 
engraving  of,  57. 
method  of  attaching,  326,  327. 
spring,  scale  of,  331. 
springs,  59,  62,  329. 
steam  engine,  111. 

Tabor,  323,  324. 
what  is  shown  by,  339,  340. 


Induced  current,  557. 

“ in  ejector,  534. 

“ “ of  air,  579, 

Inertia,  2,  6,  7. 

“ diagram  of,  110. 

“ of  moving  body,  3. 

“ “ pistons,  357. 

Initial  pressure,  70,  72,  73,  74,  339. 

Injector,  216. 

“ attachments,  235. 

“ description  of,  221. 

“ effect  of  hot  water  on,  622. 

“ fixed  nozzle,  224. 

“ Korting’s,  233. 

“ location  of,  235. 

“ Mack’s,  229. 

“ monitor,  228. 

“ Nathan  M’f’g  Co.’s,  228. 

“ rudimentary,  222. 

“ Sellers’,  225-227. 

“ simple  form  of,  224. 

“ testing  boiler  with,  599. 

“ use  of,  236,  620. 

“ water  supply  of,  463. 

Injectors,  care  of,  604,  612,  613,  614. 

“ defects  of,  613,  614. 

“ failure  of,  650. 

Injuries  to  persons,  663-673. 

Insensible  person,  treatment  of,  669. 

Inside  clearance,  97. 

“ cylinders,  126. 

“ lap,  78,  97. 

“ lead,  78. 

Inspection,  ample  time  for,  614. 

“ of  boiler,  internal,  601. 

“ “ brakes,  523,  524. 

“ “ cylinders,  pistons  and  guides, 

604. 

“ “ engine  at  stations,  633. 

“ “ locomotives,  598-616. 

Inspector,  duties  of,  610. 

Inspiration,  artificial,  673. 

Inspirator,  Hancock’s,  230-231. 

Institution  of  Mechanical  Engineers,  202. 
Instrument  for  drawing  motion  curves,  303- 
305. 

Intensity  of  combustion,  569. 

Interlocking  signals,  626,  645. 

Internal  corrosion  in  boiler,  601. 

“ disturbing  forces,  376-391. 
Introduction,  xi. 

Inversely  proportional,  31. 

Inverted  plan,  xiv. 

Iron,  conducting  and  radiating  power  of,  33. 

“ plates,  strength  of,  199. 

“ rivets,  strength  of,  199. 

“ rod,  heating  by  hammering,  35. 

“ standard,  table  of  size  of,  457. 

Jaw,  414. 

Jerking  of  train,  526. 

Jet,  of  injector,  226. 

Journal-bearings,  48,  49,  412. 

“ of  tender,  465,  466. 

“ Dox,  of  tender,  465,  466,  467. 

“ boxes,  412. 


Index. 


695 


Jou — Lea 

Journals,  heating  and  cooling  of,  633. 

“ “ of,  610. 

“ how  lubricated,  444. 

“ of  axles,  412. 

“ “ “ care  of,  610. 

“ “ crank-pins,  280,  408,  409. 

Junction  with  train,  care  in  making,  618. 

Katecliismus  der  Einrichtung  und  des 
Betriebes  der  Loco- 
motive, iii. 

“ “ locomotive,  630,  637. 

Kerosene  lamp,  556. 

Key,  49. 

“ of  journal  bearing,  465,  466,  467. 

Keys  for  connecting-rods,  277. 

“ split,  459. 

“ Kick  back,”  602. 

King-bolt  of  truck,  433. 

► “ bolts,  392,  393,  430. 

“ Knock,”  significance  of,  611. 

Koch,  R ,415. 

Korting’s  injector,  233. 

Kosack,  George,  iii,  iv,  630,  637. 

Lagging,  573. 

11  burning  of,  605. 

“ for  cylinders,  268. 

“ of  boiler,  212. 

Lake  Shore  and  Michigan  Southern  R.  R.,  595. 
Lamp-black,  radiation  from,  33. 

“ chimney,  555,  556. 

“ in  cab,  628. 

“ kerosene,  556. 

Lamps,  supply  of,  618. 

Lap,  effect  of  reducing,  345. 

“ influence  of,  342. 

“ inside,  97. 

“ of  valve,  78,  81,  82,  84,  93,  281,  320,  321, 
356. 

“ “ effect  of,  346. 

“ too  much,  338. 

“ welted  seam,  204. 

Latch  of  reversing  lever,  352. 

“ “ throttle  lever,  255-256. 

Latent  heat,  554. 

“ “ of  evaporation,  37,  38,  39. 

Laughing-gas,  553. 

Law,  Boyle’s,  30. 

“ of  motion,  1,  2. 

Laying  up  engine,  598. 

Lead,  313,  318,  319,  341. 

“ effect  of,  384. 

“ equalization  of , 341 . 

“ how  affected  by  link,  314,  315. 

“ of  valve,  78,  82,  305,  308. 

“ too  little,  336. 

“ used  for  counterweights,  379. 

Leading  engine,  529. 

Leak  at  tubes,  601. 

/%i  external  in  boiler,  601. 

“ in  stuffing-box,  606. 

“ “ valve,  337. 

Leakage,  groove,  525, 

“ of  air,  523,  525,  528. 

“ “ boiler,  significance  of,  601. 


Lea — Loa 

Leakage  of  brake-pipe,  504. 

“ “ stay-bolts,  601. 

“ “ valves  or  piston,  340. 

Leaks  in  boiler,  600. 

“ “ fire-box,  600. 

Leaky  boiler-seam,  600. 

“ flues,  600. 

“ main  valves  or  piston,  605. 

“ piston,  604. 

“ throttle-valve,  603. 

Leather  hose,  461. 

“ packing,  465,  466. 

“ pressure  of  air  on,  24. 

Legs  of  water  tank,  461. 

I Level  track,  resistance  on,  586,  587. 

! Lever,  principles  of,  19. 
j “ throttle,  255-256. 

! Leverage  on  crank-pins,  545. 

“ rules  for  calculating,  22. 

Levers,  arrangement  of  for  brakes,  518,  519. 
“ brake,  467,  483,  484,  514,  515. 

“ arrangement  of,  514,  515. 

“ “ beam,  515, 519. 

“ calculation  of,  517. 

“ rules  for  calculating,  519,  520. 
“ cylinder,  515,  519. 

“ calculation  of,  518. 

“ engravings  of,  20,  21. 

“ floating,  515,  519. 

Lifting-arm,  299. 

“ “ broken,  659. 

“ shaft,  117,  284,  356. 

“ “ broken, 660. 

“ “ position  of,  341. 

Light  fire,  561. 

“ from  flame,  556. 

Lime,  in  water,  470. 

“ precipitation  of,  472. 

Limit  gauges,  457,  458. 

“ of  elasticity,  188,  420. 

“ Line-and-line,”  308. 

Linear  advance,  343,  344. 

Liners,  in  cross-head,  607. 

Link,  117,  281,284,  356. 

“ block,  284,  286,  293,  315,  356. 

“ “ slip  of,  293. 

“ diagrams  of  movement,  316. 

“ hanger,  117,  286,  299, 

“ .adjustment  of  length  of,  356. 

“ motion,  356. 

“ “ defect  of,  349. 

“ “ diagrams  of,  287,288,290,291,292. 

“ effect  of  alterations  in,  340. 

“ engraving  of,  285. 

“ faults  of,  340. 

“ “ peculiarity  of,  335. 

“ saddle,  286. 

“ “ broken,  659. 

“ template  of,  299. 
j Links,  suspension  of,  341. 

| Liquor,  640. 

J List  of  parts  of  a locomotive,  119,  120. 
i “ Live  ” brake  lever,  519. 

Live  steam,  80,  97,  322. 

Load  locomotive  can  draw,  547. 

“ on  driving-wheels,  370,  371. 


696 


Index. 


Loc — Loc 

Lock-nut,  459. 

Locomotive  boilers,  capacity  of,  171. 

“ coal  consumed  per  mile  by,  596. 

“ compound,  126. 

“ consolidation,  123. 

“ “ dimensions  and 

weight  of,  157. 

“ “ engraving  of,  156. 

“ decapod,  123. 

“ 44  dimensions  and  weight 

of,  161. 

“ “ engraving  of,  160. 

“ end  view  of,  115. 

“ engine,  general  description  of, 

112. 

“ expenses,  proportion  of,  596. 

“ experiments,  597. 

“ firing  of,  631. 

“ for  local  passenger  service,  di- 
mensions and  weight  of,  143. 

“ “ local  passenger  service,  en- 

graving of,  142. 

“ “ street  railroads,  dimensions 

and  weight 
of,  165. 

“ “ “ “ engraving 

of,  164. 

“ “ suburban  service,  dimen- 

sions and  weight  of,  145. 

“ “ suburban  service,  engrav- 

ing of,  144. 

“ Forney,  for  New  York  Elevated 

Railroad,  dimension  and  weight 
of,  139. 

“ Forney,  for  New  York  Elevated 

Railroad,  engraving  of,  138. 

“ Forney,  for  suburban  traffic, 

dimensions  and  weight  of,  137. 
“ Forney,  for  suburban  traffic,  en- 

graving of,  136. 

“ Forney,  pony,  dimensions  and 

weight  of,  135. 

41  “ “ engraving  of, 

134. 

“ four-wheeled  switching,  dimen- 

sions and  weight  of,  129. 

“ four-wheeled  switching,  engrav- 

ing of,  128. 

frictional  resistance  of,  34. 

Grant  pony,  dimensions  and 
weight  of,  133. 

“ “ “ engraving  of,  132. 

Hudson  double-ender,  dimen- 
sions and  weight  of,  147. 

‘ ‘ Hudson  double-ender,  engraving 

of,  146. 

“ mogul,  123. 

“ “ dimensions  and  weight 

of,  153. 

“ “ engraving  of,  152. 

power  of,  545. 
principal  parts  of,  112. 

“ producing  motion,  34. 

“ stability  of.  383. 

starting,  598,  619. 

“ tank,  121. 


Loc — Mac 

Locomotive  tank,  dimensions  and  weight  of, 
163. 

“ engraving  of,  162. 
ten-wheeled,  123. 

“ “ dimensions  and 

weight  of,  155. 

“ “ engraving  of,  154. 

transverse  section  of,  114. 
twelve-wheeled,  123. 

“ dimensions  and 

weight  of,  159. 

“ engraving  of, 

158. 

Locomotives,  “ American,”  122. 

“ construction  of,  122. 

“ dimensions  and 

weight  of,  149,  151. 

“ dimensions  of,  122. 

“ “ engraving  of,  148, 150. 

“ weight  of,  122. 
care  and  inspection  of,  598-616. 
cost  of  operating,  595-597. 
different  kinds  of,  121. 

44  engineers,  responsibility  and 

qualifications  of,  637-642. 

44  escape  of,  645. 

for  N.  Y.  Elevated  R.R.,  125. 

“ street  railroads,  126. 

“ four  and  six-wheeled,  121. 

44  freight  and  passenger,  121. 

44  proportions  of,  540-550. 

44  running  of,  598,  617. 

“ six-coupled  rapid  transit,  dimen- 

sions and  weight  of,  141. 

“ six-coupled  rapid  transit,  engrav- 

ing of,  140. 

“ six-wheeled  switching,  dimen- 

sions and  weight  of,  131. 

“ six-wheeled  switching,  engrav- 

ing of,  130. 

44  switching,  124. 

u 44  shunting  and  drilling, 

121. 

London  & South  Western  Railway,  260. 

44  Loosing  fire,”  563. 

Lost  motion,  49,  280. 

44  44  effect  of,  608, 611. 

44  44  in  guides,  607. 

44  44  44  valve-gear,  313. 

Low  pressure  and  expansion,  67. 

44  4 4 steam,  expansion  of,  71. 

44  water,  239. 

Lubricant,  destruction  of,  72. 

Lubricating  material,  effect  of,  441. 
oil,  cost  of,  595. 

41  precautions  regarding,  616. 

Lubrication  and  friction,  440-450. 

of  locomotives,  598. 

14  piston  guides,  etc.,  606,  607. 

4 4 4 4 packing,  605. 

44  working  parts,  633. 

Lubricators,  sight  feed,  446,  447,  448. 

Lugs  for  cylinders,  414. 

Lye,  use  of,  532. 


ITIack’s  injector,  229. 


Index. 


69' 


Mag — Mot 

Magnesia,  precipitation  of,  472. 

Magnesium,  chloride  of,  473. 

Main  air  reservoir,  484,  487,  488,  489,  494,  495, 
497,  504,  522,  524,  527,  532. 

“ connecting-rods,  276. 

“ driving-axle,  113. 

“ “ wheels,  113. 

“ shaft,  89. 

“ valves,  leakage  of,  609. 

“ “ leak  in,  605. 

Major-force,  21,  22,  23. 

Management  of  locomotive,  598. 

Man-hole,  461,  583. 

Marine  boilers,  171. 

Master  Car  Builders’  Association,  400, 451, 452. 

“ standard  tread  and 

flange,  410,  411. 

“ Mechanics’  Association,  452,  457,  596. 

“ “ “ recommenda- 

tion of  com- 
mittee of,  541. 

Maxims,  safe,  624. 

Mean  absolute  pressure,  64. 

Mechanical  drawings,  xii. 

“ equivalent  of  heat,  34. 

Mercury  column,  247. 

Metal  packing,  47,  272. 

Metallic  piston-rod  packing,  273. 

Metropolitan  railroads,  121,  123,  124. 

“ “ locomotives  for,  125. 

Michigan  Central  Railroad,  544. 

Middle  position  of  valve,  282. 

Mid-gear,  289,  293. 

“ of  link,  321. 

Mile,  coal  consumed  per  train  and  per  car, 
595,  596. 

Milk,  use  of,  671. 

Mine,  boiling  point  in,  27. 

“ drainage,  473. 

“ pressure  of  air  in,  25. 

Minor-force,  21,  22,  23. 

Miscellaneous,  435-439. 

Mixing  of  gases,  569. 

Model  of  valve-gear,  341, 

“ “ wheels,  376. 

Modulus  of  propulsion,  544. 

“ “ traction,  545. 

Mogul  engines,  275. 

“ locomotive,  123. 

dimensions  and  weight  of, 
153. 

engraving  of,  152. 
plan  of  wheels,  403. 
Moisture  in  brake-pipes,  503. 

Molcules,  clashing  of,  560. 

Molecular  activity,  558. 

Momentum  of  piston,  94,  322,  338,  359,  369. 

“ “ diagram  of,  110. 

“ reciprocating  parts,  110,  318, 
357,  376. 

Monitor  injector,  228. 

Morin’s  Mechanics,  442. 

Morris,  George,  420. 

Motion,  34. 

“ composition  of,  14. 

“ converted  into  heat,  35. 


Mot— Off 

Motion,  curves,  89,  92.  93,  293. 

“ drawing  of,  296-305. 

“ “ engraving  of,  95,  96,  294,  306. 

307,  310,  312,  347,  348, 

“ instruments  for  drawing,  303- 
305. 

“ first  law  of,  1,  2. 

“ reciprocating,  40. 

“ resolution  of,  10,  14. 

“ rotary,  40. 

“ uniform,  2. 

Motive  power,  3,  40. 

Mould  for  chilling  wheels,  410. 

Mountain,  pressure  of  air  on  top  of,  25. 
Mountains,  boiling  point  on,  26. 

Moving  body,  velocity  of,  3. 

Mud  drum,  249. 

“ in  boiler,  621. 

“ “ water,  470,  472. 

“ plugs,  249. 

“ removal  of  from  boiler,  634. 

“ ring,  174. 

“ “ leak  at,  601. 

“ should  be  cleaned  out  of  boilers,  601. 

“ “ opening  of,  634. 

Muddy  water,  use  of,  622. 

Mufflers,  242. 

Multiplication,  xii. 

“ sign  of,  xii. 

Muscular  sense,  1. 

Nathan  M’f’g  Co..  444,  447. 

“ Co.’s  injector,  228. 

“ sight  feed  lubricator,  directions  for 
use  of,  449,  450. 

National  Tube  Works  Co.’s  injector,  229,  231. 
Navy  Department,  452. 

Netting,  212. 

“ dimensions  of,  215. 

“ wire,  care  of,  602. 

New  Chemistry,  551,  552,  555. 

New  York  Central  and  Hudson  River  Rail- 
road, 124. 

New  York  Central  and  Hudson  River  Rail- 
road fire-box,  576-579. 

New  York  City,  121. 

“ “ Elevated  Railroad,  125. 

Night,  running  a locomotive  in,  628. 

Nitric  acid,  553. 

“ oxide,  553. 

Nitrogen,  551,  552,  553,  566. 

Nitrous  acid,  553. 

“ oxide,  553. 

Noise  of  escaping  steam,  242. 

Non-conducting  material,  33,' •572. 

Northern  Pacific  Railroad,  530. 

“ Nosing,”  379. 

Nozzle,  exhaust,  260. 

“ steam,  224. 

Nozzles  for  steam  jet,  579. 

Nuts,  451,  460. 

“ shape  of,  458,  459. 

“ table  of,  454. 

“ unscrewing  of,  458,  459. 

Off  the  track,  646. 


698 


Index. 


Oil— Pas 


Pas— Pis 


Oil,  440,  450. 

" boxes,  465,  466,  467. 

“ cause  of  foaming,  623. 

" cellar,  412. 

“ cellars,  care  of,  610. 

“ “ for  connecting-rods,  280. 

“ cock,  for  cylinder,  268. 

“ cost  of,  595. 

“ cups,  444,  445. 

“ “ care  of,  614. 

“ “ for  slides,  276. 

“ destruction  of,  72. 

“ effect  of,  441. 

“ good  lubricant,  444. 

“ holes,  care  of,  608,  609. 

“ in  boiler,  621. 

“ leakage  of,  465. 

“ supply  of,  618. 

“ use  of  too  much,  602. 

Oiler,  for  cylinder,  268. 

Oiling  brake-cylinder,  531. 

“ main  valves,  625. 

“ of  locomotives,  598. 

“ “ pistons  and  valves,  268. 

“ “ slides,  276. 

“ Open  road,”  122. 

“ “ running  on,  624. 

Ordinary  stops,  525. 

Organs  of  a locomotive,  117. 

“ “ boilers,  168. 

Oscillation  of  locomotive,  425. 

“ Out  of  balance,”  376. 

Outside  cylinders,  126. 

“ lap,  78. 

“ “ of  valve,  82. 

“ lead,  78. 

Over  pressure,  causes  of,  648. 

Overflow  of  injector,  224. 

Oxygen,  551,  552,  554, 555, 556,  557, 558,  559,  560, 
561,  566,581. 


Packing,  47. 

“ for  glass  gauge,  239. 

“ “ journal  box,  465,  466. 

“ leather,  501. 

“ metal,  272,  273. 

“ nuts,  270. 

“ piston,  care  of,  605. 

“ inspection  of,  604. 

“ rings,  270. 

“ “setting  out,”  606. 

“ spring  for  pistons,  269. 

“ springs,  270. 

“ steam,  271. 

“ supply  of,  618. 

Pad,  use  of,  663,  666. 

Paint  on  smoke-box,  blistering  of,  602. 

“ “ tank,  blistered  by  heat,  622. 

Paper  wheels,  410. 

Parallel  rod,  116,  276. 

Parallelogram  of  forces,  12,  16. 

“ motion  and  forces,  engrav- 
ing of,  14. 

Parts  of  locomotive,  list  of,  119,  120. 
Passenger  locomotive,  121. 


Passenger  locomotive,  dimensions  and  weight 
of,  143. 

“ “ engraving  of,  142. 

“ service,  122. 

Passengers,  525,  527. 

Pennsylvania  Railroad  Company’s  specifica 
tions  for  boiler  and  fire-box 
steel,  190. 

“ . Road,  596,  597. 

Percussion  of  water  in  boiler,  648. 

Perfect  combustion,  568. 

Perforated  pipe,  623. 

Performance  and  cost  of  operating  locomo- 
tives, 595-597. 

Periodicals,  reading  of,  642. 

Periphery  of  wheel,  396. 

Pet-cock,  220. 

“ “ opening  of,  636. 

“ “ use  of,  650. 

Petticoat-pipe,  inspection  of,  602. 

“ position  of,  631. 

Philadelphia  and  Erie  Railroad,  596. 
Phosphate  of  soda,  472. 

Phosphates,  472. 

Pile-driver,  35. 

“ driving  machine,  38. 

Pilot,  118,  414,  437. 

“ use  of,  629. 

Pipe,  blast,  260-262. 

1 ‘ brake,  483, 484, 485, 486, 488, 489,  493,  494, 
495,  496,  497,  502,  503,  504,  509,  511,  513, 
523,  524,  525,526,  527,  529,  531. 

“ see  brake-pipe. 

“ suction,  216. 

Pipes,  dry,  steam  and  throttle,  212. 

“ exhaust,  259. 

“ feed,  216. 

“ perforated,  623. 

“ steam,  254,  255. 

“ “ size  of,  318. 

Piston,  40,  43,  46,  50,  53,  54,  §5,  87,  90,  94,  98, 
263,  280,  281,  356. 

“ acceleration  of,  106,  110,  111. 

“ action  of,  98. 

“ and  crank,  diagram  of,  86. 

“ broken,  654. 

“ diagram  of  movement,  99,  102. 

“ “ velocity  of,  105. 

“ head,  270. 

“ maximum  power  of,  116. 

“ momentum  of,  359-369. 

“ motion  of,  100,  101. 

“ packing,  270. 

“ inspection  of,  604. 

“ “ “ setting  out,”  606. 

“ rings,  604. 

“ rod,  40,  46,  47,  48,  269,  272,  275. 

“ “ weight  of,  385. 

“ rods,  bent,  605. 

“ “ care  of,  607. 

“ stroke  of,  98,  542. 

“ velocity  of,  103, 104. 

Pistons,  action  of  357,  369. 

“ area  of,  rule  for,  542. 

“ brake,  483,  501,  513,  521,  525, 

531. 


Index. 


699 


Pis— Pre 


Pre— Puf 


Pistons,  construction  of,  269. 

“ diagram  of  action  of  two,  383. 

“ how  lubricated,  446. 

“ inertia  of,  357. 

“ inspection  of,  604. 

“ oiling  of,  268. 

Pit  of  turn-table,  480. 

Pitch  of  rivets,  202,  210. 

“ “ “ rule  for,  200. 

“ “ screws,  451,  452. 

Pittsburgh  Locomotive  Works,  locomotive 
by,  156. 

Plain  fire-box,  573. 

Plan,  xiv. 

“ of  wheels,  402,  403. 

Plate,  bulging  of,  600,  601. 

Plates,  cracked  in  boiler,  601. 

“ “ “ fire-box,  600. 

“ crushing  of,  193. 

“ of  fire-box,  strain  on  and  cracking  of, 
618. 

Plugs,  for  tubes,  use  of,  649. 

“ mud,  249. 

“ safety,  239. 

Plummet-line,  389. 

Plunger,  pump,  276. 

Plus,  sign,  xii. 

Pockets,  for  coal,  473,  477. 

Point  of  compression,  295,  330. 

“ “ cut-off,  313,  314,  529. 

“ “ exhaust  closure,  330. 

“ “ pre-release,  295. 

“ “ release,  313,  314,  329,  340. 

Pole,  of  wagon,  393,  405. 

Polished  metals,  radiation  from,  33. 

Pony-truck,  125,  430,  431,  432. 

“ “ adjustment  of  to  track,  433. 

“ “ advantages  of,  434. 

Poppet  throttle-valve,  254-256. 

Port,  exhaust,  41,  46,  93,  94. 

Porter,  Charles  T.,  Ill,  324,  340. 

Ports,  50,  91,  263. 

“ area  of,  349. 

“ opening  of,  81,  82. 

“ steam,  41,  46,  93,  94,  97. 

Possible  energy,  35. 

Potential  energy,  35,  38,  71. 

“ Pound,”  cause  of,  611. 

Power,  driving  engine,  340. 

“ of  locomotive,  545. 

“ required  to  move  slide-valve,  350. 

“ tractive,  371-375. 

“ which  locomotive  will  exert,  64. 

Practical  treatise  on  steam  engine,  111. 

Pratt  & Whitney  Co.,  457. 

Pre-admission,  insufficient,  336. 

“ of  steam,  94,  295,  317. 

Precipitates,  472. 

Preface  to  first  edition,  iii. 

“ “ second  edition,  vi. 

Pre-release,  333,  341. 

“ of  steam,  317,  320,  321. 

Pressure,  absolute,  28. 

air,  excess  of,  489,  493. 

“ and  temperature  of  steam  and 
water,  28. 


Pressure,  average  in  cylinder,  rule  for  calcu- 
lating, 63. 

“ during  expansion,  340. 

“ effect  of  on  lubrication,  442. 

“ effective,  28. 

11  “ 31. 

“ final,  31. 

“ gauge,  495. 

“ “ for  vacuum-brake,  538. 

“ high,  advantages  of,  65. 

“ hydraulic,  test  of  boiler,  599. 

“ in  boiler,  541. 

“ “ diagrams  of,  185. 

“ “ reduction  of,  622. 

“ in  brake  cylinders,  517. 

“ “ cylinder,  59,  60,  63,  318,  541. 

“ “ “ effect  of,  383. 

“ increase  of,  74. 

“ of  air,  24. 

‘l  “ 525. 

“ below  piston,  engraving  of, 
“ 25. 

“ “ excess  of,  522,  525,  527,  528. 

“ reduction  of,  526. 

“ 11  variation  of,  25. 

“ of  brakes  on  wheels,  513,  514. 

“ “ steam,  26,  27,  55,  68,  543. 

“ “ “ disturbing  effect  of,  376. 

“ “ “ illustration  of,  29. 

“ “ “ indication  of,  243. 

" “ “ measurement  of,  28. 

“ “ “ or  air  after  expansion, 

30. 

“ “ “ reduction  of,  51. 

“ “ “ relation  of  to  heat  and 

volume,  56 

“ “ vacuum-brake,  538. 

on  brake-shoes,  485. 

“ “ “ calculation  for,  515- 

520. 


“ crank,  65. 

“ “ pin,  357. 

“ “ “ diagram  of,  358. 

“ on  slide-valve,  350. 

“ pistons,  effect  of,  357. 
retaining  valve,  506,  507. 

“ “ 533. 


steam,  regulation  of,  240. 
test,  in  boilers,  600. 
valve,  216. 
working,  28. 

Priming,  268. 

effect  of,  624. 
of  boiler,  621,  622. 
prevention  of,  623,  624. 

Principles  of  the  lever,  19. 

Products  of  combustion,  559. 

movement  of,  546. 

“ Prompt  aid  to  the  injured,”  669,  671,  673. 
Propelling  force,  77. 

Proportions  of  double-riveted  seams,  202. 

“ locomotives,  540-550. 
Propulsion,  modulus  of,  544. 

Prosser’s  tube  expander,  engravings  of,  181. 
Protection  of  cylinders,  336. 

“ Puffs  ” of  steam,  effect  of  many,  549. 


700 


Index. 


Pul— Rai 


Rai— Res 


Pulse,  670. 

Pump,  engraving  of,  217, 

“ feed,  216. 

“ force,  598. 

“ governor,  500,  524. 

“ lug,  276. 

“ plunger,  216,  276. 

“ plungers,  bent,  605. 

“ water  supply  of,  463. 

Pumps,  air,  484,  493,  497,  498,  521,  524,  528. 

“ “ care  of,  521,  531,  532. 

“ effect  of  hot  water  on,  622. 

“ failure  of,  650L 

“ how  worked,  276. 

“ location  of,  220. 

“ use  of,  620. 

Punching  boiler  plates,  195. 

“ injury  to  plates  by,  192. 

Pure  water,  need  of,  602. 

Pusher,  529. 

Pushing-bar,  437. 

Pyrometer,  571. 

Quadrant,  352. 

Quadruple  rivets,  208. 

Quadrupling,  expansion,  74. 

Qualifications  and  responsibilities  of  locomo- 
tive engineers,  637-642. 

Quick-acting  brake,  520. 

“ “ “ pressure  in,  517. 

“ “ triple-valve,  504,  507,  508  , 510, 

511,  512,  513,  523,  530. 

“ stop,  526. 

Radial  axles,  397. 

“ stays,  176. 

“ “ engravings  of,  177. 

Radiating  power  of  substances,  32. 

“ properties  of  substances,  37. 

Radiation  from  boiler,  212. 

“ “ cylinders,  71. 

“ “ inside  cylinders,  127. 

“ loss  of  heat  from,  336. 

“ of  heat,  32,  75,  370. 

“ “ “ from  boiler,  212. 

“ “ “ loss  by,  37. 

Radii  of  curves,  392,  395,  591. 

table  of,  592,  593. 

Rail  joints,  415,  432. 

Railroad  crossing,  626,  628. 

“ curves,  method  of  laying  out,  590, 
591. 

Railroad  track,  danger  of  being  on,  664. 

Railroads,  horse,  123. 

“ in  cities,  123,  124. 

“ metropolitan,  121,  123,  124. 

“ suburban,  121,  123,  124. 

Rails,  112. 

“ condition  of,  370, .371. 

“ crushing  of,  116. 

“ difference  in  length  of  on  curves,  395. 
“ frosty,  371. 

“ greasy,  371. 

“ muddy,  371. 

“ sanded,  371. 

“ weight  on,  540. 


Rails,  wet,  371. 

Railway  machinery,  391. 

Rain  storms,  running  in,  629. 

Rankine,  568,  571. 

Rate  of  combustion,  562. 

Ratio  of  expansion,  64,  68. 

Reaming  rivet  holes,  192. 

Recharging,  air  reservoirs,  526. 
Reciprocating  motion,  40. 

parts,  acceleration  and  retarda- 
tion of,  369. 

“ “ “ of,  106. 

“ centrifugal  force  of,  357. 
“ force  required  to  move, 
107. 

“ how  balanced,  379. 

“ momentum  of,  110,  338, 
357,  376. 

“ power  required  to  move, 

“ “ weight  of,  385. 

Reconversion  of  steam  to  water,  31. 
Reduction  of  air  pressure,  526. 
Re-evaporation  in  cylinders,  340. 

Reflector  of  head-light,  436. 

Relation  between  heat  pressure  and  volume 
of  steam,  56. 

Release,  321. 

“ and  application  of  brakes,  526,  528. 

“ cock, 530. 

“ equalization  of,  100. 

“ of  air-brakes,  527,  528. 

“ “ brakes,  485,  488,  496,  497,  504,  522, 

“ “ “ on  car,  530. 

“ “ steam,  82,  97,  293,  317,  331. 

“ “ vacuum  brake,  538. 

“ point  of,  295,  313,  314,  329. 

11  too  late,  337. 

“ valve,  of  vacuum  brake,  538. 

Repairing  engines,  634. 

Repairs,  cost  of,  595. 

“ precautions  relating  to,  615. 

Report  on  riveted  joints,  202. 

Repulsion  of  particles  of  gas,  29,  38. 

Reserve  engine,  629. 

Reservoir,  air,  482,  483. 

“ auxiliary  air,  484,  485,  486,  488,  489, 
493,  503,  504,  506,  507,  509,  510,  512, 
513,  523,  524,  525,  526,  530. 

“ engineer’s  brake- valve,  486,  494, 
495 

“ main  air,  484, 487,  488,  489,  494,  495, 
497,  504,  522,  524,  527,  532. 
Reservoirs,  air,  recharging,  526. 

Resistance,  34. 

“ of  cars  on  sanded  rails,  619. 

“ “ trains,  540,  585,  594. 

“ “ “ at  different  velocities, 

586,  587. 

“ “ “ effect  of  curves  on,  590- 

“ “ “ tables  of,  588, 589. 

“ on  grades,  rule  for,  587. 

“ per  ton  of  train,  587. 

“ to  force,  3. 

Resolution  of  motion  and  forces,  10,  11. 

“ “ motions,  14. 


Index. 


701 


Res— Rod 


Rod— Run 


Respiration,  artificial,  672. 

Responsibilities  and  qualifications  of  locomo- 
tive engineers,  637-642. 

“ of  locomotive  engineers,  638. 

Resultant,  13,  16. 

Retaining  rings,  407,  410. 

“ valve,  506,  507. 

Retardation  of  reciprocating  parts,  111,  369. 
Retarded  motion,  2. 

Retarding  effect  on  piston,  334. 

Reversal  of  engine,  49. 

Reverse-lever,  286. 

44  “ broken,  660. 

“ 11  position  of  during  stops,  645. 

“ 44  “ “ when  steam  is  shut 

off,  627. 

“ 44  use  of,  619. 

“ rod, 286. 

“ “ broken,  660. 

Reversing  engine  in  danger,  644. 

“ gear,  354. 

“ lever,  117,  352,  353,  355. 

“ rod, 117. 

“ shaft,  356. 

Revolution  of  wheels,  112. 

Revolving  parts,  action  of,  376. 

44  44  weight  of,  385. 

“ shaft,  effect  of,  376. 

44  weights,  379. 

“ “ centrifugal  force  of,  380. 

“ wheel,  effect  of,  376. 

Richard’s  steam  engine  indicator,  111,  340. 

44  “ indicator,  324. 

Richardson’s  balance  valve,  350,  351. 

“ safety-valve,  240,  241. 

River,  11. 

Rivet-head,  size  of,  209. 

“ holes,  drilled,  198. 

“ 44  matching  of,  196. 

44  “ reaming  or  drilling  of,  192. 

Riveted  seams,  proportions  of,  199. 

“ 44  strength  of,  191. 

44  44  table  of  strength  of,  201. 

44  44  welted,  206. 

Riveting,  191. 

44  machine,  197. 

Rivets,  crushing  of,  193. 

44  diameter  of,  197. 

44  quadruple,  208. 

44  quality  of,  188,  189. 

44  rule  for,  pitch  of,  199. 

44  shearing  of,  193. 

44  size  of,  210. 

44  steel,  190. 

44  strength  of,  191. 

44  44  44  steel,  190. 

44  testing  of,  189. 

Rocker,  43,  84,  89,  92,  117,  281,  286. 

44  arms,  90,  281. 

44  44  length  of,  301. 

“ broken,  659. 

44  pin,  286,  289,  293,  296,  301,  315,  356. 

44  shaft,  289,  293,  296. 

Rocking-grate,  252. 

44  of  engine,  379. 

Rod,  coupling  or  parallel,  116, 


Rod,  eccentric,  85. 

Rods,  connecting,  263-280. 

Rogers’  Locomotive  and  Machine  Works, 
locomotive  by,  130,  144,  146. 

Rolling  of  engine,  379. 

4 4 4 4 locomotive,  391. 

Rome  Locomotive  Works,  locomotive  by,  138. 
Roof,  17. 

44  truss,  engraving  of,  17. 

Rooms,  ventilation  of,  640. 

Rotary  motion,  40,  41 . 

44  valve,  493,  494,  495,  496,  497. 

Rotative  effect  on  crank,  360-369. 

44  44  44  pin,  diagram  of, 

361,  365,  368. 

44  44  44  rule  for,  363. 

44  4 4 variation  of,  366. 

Round  rolled  iron,  table  of  size  of,  457. 
Roundhouses,  480. 

Rowland,  Prof.,  36. 

Rubber  hose,  463. 

44  packing,  239. 

Rule  for  ascertaining  pressure  after  expan- 
sion, 30. 

4 4 4 4 calculating  area  of  pistons,  542. 

centrifugal  force,  108. 
diameter  of  cylinders, 
542. 

resistance  on  grades, 
587. 

rotative  effect  on  crank, 
363. 

strain  on  boiler,  184. 
the  resistance  of  cars, 
586. 

“ strength  of  boiler 
seams,  193. 

44  “ velocity  of  a falling 

body,  6. 

44  tractive  power,  372. 

44  4 4 44  work,  34. 

4 4 4 4 determining  speed  of  engine,  597. 

44  4 4 modulus  of  propulsion,  544. 

4 4 4 4 standard  screw  threads,  455. 

44  relating  to  crossing  railroads,  645. 

Rules  for  calculating  counterweights,  389- 


elasticity,  deflection, 
span,  number  of 
plates,  strength,  etc. 
of  springs,  423,  424. 
brake  levers,  519, 
520. 


44  44  44  leverage,  22. 

44  44  firing,  633. 

44  44  the  use  of  air-brakes  on  Northern 

Pacific  Railroad,  530. 

Runaway  locomotives,  645. 

Running  at  night,  628. 

44  boards,  437. 

44  down  grades,  626. 

44  engine  economically,  620. 

44  gear,  392-434. 

44  care  of,  610. 

44  into  stations,  627. 

44  locomotive,  598,  617, 


702 


Index. 


Run — Sel 

Running  on  a curve,  624. 

“ “ open  road,  624. 

“ streams,  472. 

Russia  iron,  33,  212,  268. 

Rust  on  outside  of  boiler,  601. 

Saddle,  for  link,  286. 

Saddles,  416. 

Safety-chains,  118,  439,  465 
“ plugs,  239. 

“ valves,  240. 

“ “ care  of,  603,  604. 

“ “ defects  of,  648. 

“ “ effect  of  blowing  off,  622. 

“ “ examination  of,  649. 

Sand-box,  118. 

“ “ care  of,  615. 

“ “ construction  of,  435. 

“ “ use  of,  619. 

“ effect  of  on  resistance  of  cars,  619. 

“ little  should  be  used,  619. 

“ valves,  use  of,  644. 

Sanded  rails,  371. 

Saturated  steam,  28. 

Scalds,  treatment  of,  671. 

Scale  in  boiler,  470,  472. 

“ making  material,  472. 

“ removal  of  from  boiler,  634. 
Schenectady  Locomotive  Works,  locomotives 
by,  136,  158. 

Scheurer-Kestner,  M.,  568,  570. 

Schutte  & Co.’s  injector,  233. 

Scoop,  water,  462,  463, 

Scrapers,  437. 

Screw  coupling,  463. 

“ plugs,  249. 

“ single,  double  and  treble  threaded, 

451. 

“ thread,  angle  of,  453. 

“ “ gauge,  455, 456. 

“ threads,  bolts  and  nuts,  451-460. 

“ “ form  of,  451, 452. 

11  “ standard  system  of,  452-458. 

“ “ table  of  standard,  454. 

Screws,  451. 

“ diameters  of,  456. 

Seam,  breaking  of,  193. 

“ calculation  of  strength  of,  193. 

“ leaky,  600. 

“ strength  of,  205. 

Seams,  comparison  of,  strength  of,  198. 

“ riveted,  proportions  of,  199. 

“ “ strength  of,  191. 

“ single  riveted,  194. 
li  weakness  of,  191. 

“ welted,  206. 

Sea  shore,  473. 

Section,  xiv. 

“ of  locomotive,  114. 

Sectional  plan,  xv. 

“ view,  xiv. 

Sector,  552,  555. 

Sellers,  Coleman,  647. 

“ William,  452. 

“ “ & Co.,  479.  [455, 458. 

Sellers’  system  of  screw  threads,  452,  453,  454, 


Sel-Sli 

Sellers’  system  of  screw  threads,  table  of,  454 
“ turn-table,  478,  479. 

Service  of  engineers  and  firemen,  595. 

“ stops,  495,  525,  526. 

Set,  188. 

“ screws,  for  connecting-rods,  277. 

“ “ “ eccentrics,  356. 

Setting  a slide-valve,  354,  355,  356. 

I “ Setting  out  packing,”  606. 

Shaft,  41,  85,  87. 

“ brake,  486. 

“ effect  of  revolving,  376. 

Shafts  of  wagon,  393. 

Shaking-grate,  252. 

Shearing  of  rivets,  193. 

Sheffield  Velocipede  Car  Co.,  470. 

Shims  in  cross-head,  607. 

Shock,  danger  from,  665. 

“ or  collapse,  669,  671. 

“ symptoms  and  treatment  of,  670,  671. 
Shocks,  effect  of  on  engineer,  637. 

Shoes,  416. 

“ brake,  467,  482,  483,  484,  503. 

“ pressure  on,  485. 

Shovel,  feeding  fire  with,  563. 

“ inverted,  574. 

Show  windows,  559. 

Shunting  locomotives,  121. 

Shutting  off  steam,  627. 

Sickness,  preservation  of,  639. 

Side-bearing,  467. 

“ rods,  276. 

“ view,  xiv. 

“ Sight-feed  lubricators,”  446,  447,  448. 

Signal,  certainty  of,  627. 

“ gong,  435. 

Signals,  615. 

“ in  fogs,  629. 

“ interlocking,  626. 

“ “ and  distant,  645. 

“ observation  of,  619,  624. 

“ on  engine,  628. 

Silver,  radiation  from,  33. 

Single  riveted  seams,  194. 

“ “ “ proportions  of,  199. 

“ “ “ table  of,  194. 

“ threaded  screw,  451. 

Six-coupled  rapid  transit  locomotive,  dimen- 
sions and  weight 
of,  141. 

“ “ locomotive,  engrav- 

ing of,  140. 

“ wheeled  locomotives,  121. 

“ “ switching  locomotive,  dimen- 

sions and  weight  of, 
131. 

locomotive,  engrav- 
ing of,  130. 

“ “ trucks,  126, 517. 

Size  of  driving-wheels,  effect  of,  549. 

“ Slack  of  train,”  taking  up,  619. 

“ Slewed  ” truck  wheels,  400,  401. 

Slack  in  brake  connections,  521. 

Slide-valve,  41,  78,  267. 

“ “ action  of,  340. 

“ “ condition  fulfilled  by,  78,  80. 


Index. 


703 


Sli— Spe 

Slide-valve,  effect  of  steam  on,  350. 

“ engravings  of,  79,  80. 

“ “ how  lubricated,  446. 

“ “ motion  of,  82. 

“ “ oiling  of,  268. 

“ “ power  required  to  move.  350. 

“ “ proportions  of,  81. 

“ “ setting  of,  354,  355,  356. 

Slides,  100,  101. 

“ care  of,  607. 

“ wear  of,  275. 

Sliding  of  wheels,  395. 

Slip  of  driving-wheels,  370. 

“ “ link-block,  293. 

“ “ wheels,  112,  395,  397,  541,  619. 

Slipping  of  wheels  on  curves,  395. 

Smith,  A.  F.,  125. 

Smoke,  117,  555,  556,  561. 

“ box,  117, 168,  212. 

“ “ door,  fastening  of,  602. 

“ “ extended,  582,  583,  584. 

“ “ influence  of  on  combustion,  581. 

“ “ inspection  of,  602. 

“ “ section  of,  114. 

“ “ temperature  in,  571. 

“ consumption  of,  561. 

“ prevention  of,  631,  633. 

“ stack,  117, 118, 168,  171. 

“ stacks,  construction  of,  215, 

“ “ engravings  of,  213, 214. 

“ “ height  of,  215. 

Snow,  629. 

“ and  rain  storms,  running  in,  629. 

“ melting  of  for  water,  662. 

“ on  rails,  371. 

“ plow,  use  of,  629. 

“ storm,  662. 

Soap,  473. 

“ in  boiler,  621. 

Sobriety,  importance  of,  638. 

Soda,  phosphate  of,  472. 

“ water,  621. 

Solid  matter  in  water,  470,  472,  601,  602. 

Soot,  555,  556,  560,  561 . 

“ removal  from  tubes,  635. 

Space  swept  by  piston,  332. 

Spark  deflector,  213. 

Sparks,  212. 

“ arrest  of,  118,  171. 

“ collection  of,  582,  584. 

“ escape  of,  602. 

Specifications,  for  boiler  and  fire-box  steel, 
190. 

Speed,  acceleration  of,  375. 

“ at  night,  628. 

“ effect  of,  624. 

“ on  resistance  of  cars,  586. 

“ high,  97. 

“ of  engines,  546. 

“ “ piston,  opening  required  for,  349. 

“ “ locomotive,  545. 

“ “ train,  540. 

“ reduction  of,  620. 

“ rule  for  determining,  597. 

“ should  be  uniform,  620. 

Speeds,  high,  area  of  ports  for,  349, 


Spe— Sta 

Speeds,  tables  of  resistance  at,  588,  589. 

Spherical  joints,  257,  260. 

“ Spider,  270. 

Spinning-top,  376. 

Splint,  669. 

Split  keys,  459. 

Spokes,  379. 

“ hollow,  407. 

“ Spread  ” of  wheels,  406. 

u Spreading  system  ” of  firing,  632. 

Spring  band,  518,  420. 

“ broken,  655,  657. 

“ elasticity  of,  420,  421. 

“ expander,  181. 

“ for  counterbalancing  link,  354. 

“ hangers,  416,  424. 

broken, 655. 

“ care  of,  612. 

“ indicator,  59,  329. 

“ scale  of,  331. 

“ proportions  of  plates,  421. 

“ saddles,  416. 

“ strength  of,  421. 

Springs,  care  of,  612. 

“ construction  of,  416-424. 

“ curve  of,  419,  420. 

“ elasticity  of,  416. 

“ engravings  of,  413,  417,  418,  419,  420, 

“ of  truck,  428. 

“ packing,  269,  270. 

“ rules  for  calculating,  423. 

“ truck,  arrangement  of,  434. 

“ use  of,  415. 

Square,  bolt  heads  and  nuts,  458,  459,  460. 

Stability,  effect  of  connecting-rods  on,  391. 

“ of  locomotive,  383. 

Staggered  rivets,  200. 

Standard  screw  threads,  rule  for,  455. 

“ “ table  of,  454. 

“ sizes  of  bolt  heads  and  nuts,  454, 460. 

“ “ tires  and  wheel  centres,  408. 

“ system  of  screw  threads,  452-458. 

“ thread  and  flange,  410,  411. 

Stand-pipe,  470,  471 . 

Starch,  to  prevent  leaks  in  boiler,  600. 

Starting  fire,  617. 

“ locomotive,  598  619,. 

Station,  arrival  at,  633. 

“ coaling,  474. 

“ running  into,  627. 

Stationary  boilers,  171. 

“ engines,  49. 

Stay-bolts,  174. 

“ breaking  of,  179,  599. 

“ broken,  601. 

“ defective,  600. 

“ drilling  of,  175. 

“ engraving  of,  175. 

“ arrangement,  175. 

“ examination  of,  649. 

“ leakage  of,  601. 

“ strain  on,  175,  176,  177,  618. 

“ test  of  with  hapimer,  601. 

“ tubular,  574. 

Stayed  surfaces,  examination  of,  599, 


704 


Index. 


Sta— Ste 


Ste — Str 


Stays,  broken,  599. 

“ design  and  construction  of,  178. 

“ in  boiler,  defects  in,  601. 

“ radial,  176. 

Steam,  46 

“ admission  and  exhaust  of,  91. 

“ “ of,  50, 293. 

“ amount  generated  in  boiler,  546. 

“ and  air,  forces  of,  24. 

“ “ water,  pressure  and  temperature 

of,  28. 

“ “ “ volume  of,  31. 

“ car,  126. 

“ “ dimensions  and  weight  of,  167. 

“ “ engraving  of,  166. 

“ chests,  41,  267. 

“ “ broken,  654. 

“ “ lagging  for,  268. 

“ condensation  of,  31. 

“ curve,  93. 

“ cylinders,  263. 

“ definition  of,  25. 

“ diminishing  pressure  of,  51. 

“ distribution  of,  315,  540. 

“ dome,  211. 

“ drawn  from  dome,  622. 

“ edge,  of  valve,  308. 

“ efficiency  of,  68. 

“ engine  indicator,  111. 

“ “ treatise  on,  111. 

“ engines,  40, 112. 

“ escape  of,  50. 

“ exhaust  of,  97. 

“ expansion  of,  29,  36,  51,  54. 

“ expansive  action  of,  50. 

“ “ force  of,  40. 

“ friction  of,  340. 

“ gauge,  243-247,  571. 

“ “ accuracy  of,  247. 

“ “ Ashcroft,  246. 

“ “ examination  of,  649. 

“ “ lamp  for,  628. 

“ “ pipe,  247. 

“ “ tube,  244. 

“ gauges,  care  of,  604. 

“ graduation  of,  29. 

“ generating  capacity  of  boilers,  546. 

“ generation  of  in  boiler,  600. 

“ “ “ largest  quantity,  631. 

“ getting  up,  598. 

“ hammers,  9. 

“ heat  required  to  generate,  59. 

' “ high  pressure  and  expansion,  67. 

“ indicator,  323. 

“ “ cards,  engravings  of,  61. 

“ “ diagram,  61,  63. 

“ “ engraving  of,  57. 

1 1 invisible,  26. 

“ jet,  579. 

“ line,  329. 

‘ ‘ measurement  of  pressure,  28. 

“ noise  of  escaping,  242. 

‘ ‘ nozzle,  224. 

“ packing,  271. 

‘ ‘ passages,  41 . 

“ pipe  joints,  257,  260. 


Steam  pipes,  212,  254,  255,  267. 

“ “ broken,  654. 

“ “ care  of,  603. 

“ ports,  41,  46,  50,  51,  80, 81,  89,  93,  94,  97, 
263,  267. 

“ “ opening  of,  82. 

“ “ too  small,  336. 

“ “ variable  size  of  openings  of, 


pressure,  543. 

“ and  volume  of,  68. 

“ illustration  of,  29. 

“ in  boiler,  541. 

“ “ cylinder,  60,  62. 

“ indicated  by  gauges,  604 

“ indication  of,  243. 

“ of,  26. 

“ “ 27,  55. 

“ regulation  of,  240. 

“ rise  of,  649. 

k‘  shown  by  indicator,  339. 

“ test  of  boiler,  599. 

rapidity  of  generation  of,  584. 
release  of,  97,  293. 
room,  too  little,  622. 
saturated,  28. 
shutting  off,  627. 
space,  211. 
superheated,  28. 
supply  of,  547. 
tight,  46. 
total  heat  of,  39. 
using  expansively,  70,  71. 
volume  of,  30. 
ways,  97,  317,  321,  322,  332. 
wet  and  dry,  211. 

“ “ effect  of,  624. 

whistle,  247,  248. 

Steel  brittle,  191. 
ductile,  191. 
for  boilers,  187. 


“ plates,  174. 

“ “ annealing  of,  192. 

“ “ strength  of,  191,  199. 

“ rivets,  190. 

“ “ strength  of,  190,  199. 

“ strength  of,  188. 

“ tired  wheels,  410. 

Steps,  439. 

Stevens’  brake,  515,  516,  519. 

Stewart  Balfour’s  books,  note  to,  33. 

Stone,  108.  -a 

“ fall  of,  4, 

Stop-cock,  523,  529.  j 

“ quick,  526. 

Stopping  engine  and  train,  598.  u 

Stops,  exhibition,  527. 

“ ordinary,  525. 

“ satisfactory,  526. 

“ service,  495,  525,  526. 

Storms,  running  in,  629. 

Straight  air  brake,  483,  504. 

“ edge,  use  of,  599. 

“ line,  resistance  on,  586,  587. 

Strain  of  compression,  16. 

“ “ tension,  16. 


Index. 


705 


Str — Swi 

Strain  on  boiler  plate,  187. 

Strainer,  463. 

Strainers,  care  of,  615. 

“ cleaning  of,  635. 

Strap,  49. 

“ eccentric,  84,  85. 

“ end,  48,  277. 

Straps  for  connecting-rods,  277. 

Streams,  running,  472. 

Street  railroad  locomotive,  dimensions  and 
weight  of,  165. 

“ “ “ engraving  of, 

164. 

railroads,  locomotives  for,  126. 
Strength  of  boiler  plate,  187. 

“ “ material,  ultimate,  600. 

“ ultimate,  188. 

Stroke,  lengthening  of,  74. 

of  cylinders,  advantage  of  short,  550. 
“ “ piston,  50,  51,  91,  98,  542. 

“ “ “ 56. 

Strong  drink,  injury  of,  637. 
c tub-end,  48,  277. 

_tud,  460. 

Studies  for  engineers  and  firemen,  642. 
Stuffing-box,  47,  216,  267,  272. 

“ “ leaky,  606. 

Subtraction,  xii. 

Suburban  passenger  locomotive,  dimensions 
and  weight 
of,  145. 

“ “ “ engraving 

of,  144. 

“ railroads,  121.  123,  124. 

“ ‘ locomotive  for,  125. 

Suction  pipe,  216. 

“ pipes,  freezing  of,  221. 

“ valve,  216. 

Sulphates  of  iron,  473. 

Sulphur,  552,  584. 

Sulphuric  acid,  473. 

Sum,  xii. 

Sunlight,  need  of  for  health,  639,  640. 
Sun-stroke,  treatment  of,  672. 

Superheated  steam,  28. 

Superior  officers,  behavior  towards,  641. 
Supplies,  miscellaneous,  cost  of,  595. 

Supply  of  air,  control  of,  563. 

“ “ steam,  547. 

“ pipe,  463. 

ouriace  cock,  623. 

“ condenser,  124. 
cuspended  cannon-ball,  engraving  of,  1. 

“ weight,  381. 

spension-link.  adjustment  of  length  of,  356. 
“ of  links,  341. 

owash  of  water,  464. 

“ plates,  464. 

Swing-bolsters,  430. 

“ motion-truck,  430. 

Switches,  121. 

definition  of,  392. 

“ position  of,  619. 

Switching  engines,  management  of,  630. 

“ locomotive,  engraving  of,  128,  129. 

“ locomotives,  121, 124. 


Tab— Ten 

Table  of  proportions  of  butt-seams,  209. 

“ double  riveted 
seams,  202. 

“ “ standard  size  of  round  rolled  iron, 

457. 

“ “ strength  of  riveted  seams,  201. 

Tables  of  deflection  angles  and  radii  of,  592, 
593. 

“ “ resistance  of  trains,  588,  589. 

Tabor  indicator,  323,  324. 

Tail-end  collisions,  644. 

Tallow,  268. 

Tangential  angle,  590,  591. 

Tank,  118. 

“ cleaning  of,  635. 

“ engines,  118. 

“ escape  of  steam  to,  622. 

“ examination  of,  633. 

“ locomotive,  dimensions  and  weight  of . 
163. 

“ engraving  of,  162. 

“ locomotives,  121. 

“ of  tender,  461. 

“ should  be  filled,  618. 

“ staying  of,  463. 

“ valve,  220. 

“ “ 470. 

“ water,  care  of,  615. 

Tanks,  water,  469-481. 

Taps,  457. 

Taunton  Locomotive  Manufacturing  Co., 
locomotive  by,  142. 

Tea-kettle,  27. 

“ use  of,  640. 

Temperance,  641. 

“ need  of,  637. 

Temperature  and  pressure  of  steam  and 
water,  28. 

igniting,  554,  555,  559. 

“ in  cylinder,  77. 

“ fire-box,  559,  570. 

“ smoke-box,  571. 
of  escaping  gases,  571. 

“ gases  in  tubes,  571. 

“ “ steam,  71. 

“ “ diagram  of,  52. 

. “ “ effect  of,  31. 

“ “ water,  26. 

Templet  for  counterweights,  389. 

‘‘  of  link,  299. 

Ten  commandments,  641. 

“ wheeled  locomotive,  123. 

dimensions  and 
weight  of,  155. 

“ “ “ engraving  of,  154. 

Tenacity  of  boiler  plates,  188. 

Tender,  118,  461,  468. 

“ brakes,  inspection  of,  614. 

“ cleaning  of,  635. 

“ connection  of  to  engine,  465. 

“ engravings  of,  following  page  460, 

and  facing  page  461  and  on  462. 

“ frame,  461. 

“ tank,  461,  463. 

“ “ staying  of,  463. 

“ truck,  465,  466. 


706 


Index, 


Ten— Tir 

Tender  valve,  463,  464. 

“ valves,  closing  of,  636. 

“ water  supply  of,  469. 

Tensile  strength  of  boiler  plate,  187. 

Tension,  16. 

Test,  cold  water,  598. 

“ hydraulic,  600. 

“ of  boiler  by  hydraulic  pressure,  599. 

“ “ “ with  injector,  599. 

“ “ “ “ steam  pressure,  599. 

“ “ brake,  524. 

“ “ old  boilers,  600. 

“ pressure  in  boilers,  600. 

“ warm  water,  598,  600. 

Testing  boilers,  598. 

“ of  boiler  plate,  189. 

“ “ rivets,  189. 

Tests  of  boiler  plate,  190. 

Theoretical  economy  of  expansion,  70. 
Thermometer,  radiation  from,  33. 
Thermometers,  note  to,  36. 

Thigh,  injury  in,  668. 

Thimbles,  581. 

Thirst  of  wounded  persons,  668. 

Thread,  angle  of,  453. 

Threads,  form  of,  452,  453. 

“ number  to  inch,  453,  454,  458. 

“ of  screws,  451. 

“ “ “ form  of,  451,  452. 

“ screw,  standard  system  of,  452-458. 

“ standard,  table  of,  454. 

Three-legged  principle,  430. 

“ stool,  427. 

“ way  cock,  506. 

Throttle,  81. 

“ lever,  255-256. 

“ pipe,  212. 

“ stem,  255-256. 

“ valve,  65,  254. 

“ “ care  of,  603. 

1 “ closed  and  secured,  617. 

“ “ effect  of  opening  suddenly, 

621,  648. 

“ “ failure  of,  661. 

“ “ importance  of  closing  and 

fastening  of,  645. 

“ “ opening  of,  318. 

“ “ use  of,  619,  644. 

Throttling,  65. 

“ steam,  620. 

Throw  of  eccentric,  43,  78,  314. 

“ “ “ influence  of  on  cut-off, 

344. 

“ “ eccentrics,  effect  of  length  of,  346, 

349. 

“ “ “ influence  of,  342. 

“ “ valve,  influence  on  width  of  exhaust 

port,  349. 

“Throwing  fire,”  602. 

Thumb  tool,  183. 

“Thump,”  cause  of,  611. 

Thump  of  piston,  317. 

Tide,  13. 

Time  table,  629. 

Tires,  113. 

“ broken,  655. 


Tir— Tri 

Tires,  care  of,  610. 

“ fastening  of,  407. 

“ * flangeless,  405. 

“ fracture  of,  610. 

“ heating  of,  530. 

“ material  of,  370. 

“ shrinking  of,  113. 

“ standard  sizes  of,  4C8. 

T-iron,  464. 

Tongue  of  wagon,  405. 

“ pressure  of  air  on,  24. 

Tool-car,  647. 

“ for  cutting  screw-threads,  453. 

Tools,  supply  of,  618. 

“ to  be  carried,  615. 

Top,  spinning  of,  2,  376. 

“ view,  xiv. 

Total  heat  of  combustion,  560,  569. 

“ “ “ compressed  steam,  322. 

“ “ “ steam,  39,  67,  68,  70. 

“ “ “ “ diagram  of,  52. 

Toughness  of  boiler  plates,  188. 

Towing  engine,  653,  655. 

T-pipe,  257. 

Track,  112. 

“ danger  of  being  on,  664. 

“ diagram  of  action  of  wheels  on,  393. 

“ engine  off  of,  646. 

“ inequalities  of,  432. 

Traction  and  adhesion,  370-375. 

“ modulus  of,  545. 

Tractive  force,  367,  371. 

“ “ amount  of,  541,  542. 

“ “ how  exerted,  372-375. 

“ power,  371-375. 

“ “ diagram  of,  374. 

“ “ rule  for,  372. 

Trailing  wheels,  116. 

Train,  524. 

“ broken  in  two,  485,  532,  626. 

“ front  end  of,  529, 

“ jerking  of,  526. 

“ mile,  cost  of,  595,  596. 

“ motion  of,  619. 

“ protection  of,  647. 

“ rear  end  of,  529. 

“ resistance  of,  540. 

“ weight  of,  540. 

Trains,  effect  of  curves  on  resistance  of,  590. 
“ resistence  of,  585-594. 

“ “ “ at  different  velocities, 

586,  587. 

“ tables  of  resistance  of,  588,  589. 
Transmission  of  heat,  561. 

Transverse  section,  xv. 

Travel  of  valve,  78,  211,  286,  313,  314,  321,  356. 
“ “ “ effect  of  reduction  of,  93. 

“ “ “ variation  of,  293. 

Tread  and  flange,  shape  of,  410. 

“ of  wheel,  construction  of,  410. 

“ “ “ definition  of,  396. 

Treatise  on  steam  boilers,  553. 

“ “ “ engine,  111. 

Treble  threaded  screw,  451. 

Trigger  of  reversing  lever,  352. 

“ “ throttle  lever,  255-256. 


Index. 


707 


Tri— Unb 


Unb— Val 


Triple-valve,  484,  485,  486,  487,  489,  493,  494, 
496,  497,  501,  504,  507,  523,  530. 

“ “ quick  acting,  504,  507,  508,  510, 

511,  512,  513,  523,  530. 

“ valves,  care  of,  532. 

Tripod,  427 
Trough,  water,  462. 

Truck,  adjustment  of  to  track,  433. 
axles,  action  of,  395. 

“ distance  apart,  400. 

Bisseli,  125. 
boxes,  428. 
construction  of,  427. 
description  of,  392. 
engraving  of  four-wheeled,  429. 
frame,  428. 

pony  or  Bisseli,  430,  431,  432. 

“ “ advantages  of,  434. 

springs,  428. 

“ arrangement  of,  434. 
tender,  465,  466. 
wheel  or  axle  broken,  655. 
wheels,  116. 

“ construction  of,  409. 

“ engraving  of,  410.  • 

“ use  of,  392. 

with  single  pair  of  wheels,  123, 395, 404. 
Trucks,  connection  with  driving-wheels,  432. 

six-wheeled,  126,  427,  517. 

Try-cocks,  236. 

Tube,  bursting  or  collapse  of,  649. 
expander,  182. 

Dudgeon’s,  183. 

Prosser’s,  181. 

“ engraving  of,  181. 
use  of,  600. 

plate,  179. 

“ cracks  in,  601. 
plates,  strain  on,  617. 

Tubes,  117,  168. 

arrangement  of,  179,  180. 
cause  of  leaking,  623. 
cleaning  of,  602,  633. 
combustion  in,  565,  574. 
expansion  of,  618. 
fastening  of,  182. 
inclination  of,  on  grades,  625. 
leaky,  601 . 

number  of,  in  boiler,  117. 
removal  of,  601,  602. 
size  of,  173. 

Turn-tables,  469,  475,  476,  477,  478,  479,  481. 

“ diameter  of,  480. 
Twelve-wheeled  locomotive,  123. 

“ dimensions  and 

weight  of,  159. 

“ engraving  of, 

158. 

Two  engines  to  one  train,  527,  529. 

Tyndall,  note  to,  35. 


Ultimate  strength,  188. 

“ of  material,  600. 
“ “ “ spring,  420. 

Unbalanced  weight,  effect  of,  377. 


Unbalanced  weights,  effect  of,  376,  377 
Unburned  fuel,  570. 

Unguent,  effect  of,  441. 

Uniform  motion,  2. 

Uniformly  accellerated  motion,  2. 

“ retarded  motion,  2. 

Unit  of  heat,  work  done  per,  67. 

United  States  Metallic  Packing  Co.,  272. 

“ “ standard  system  of  screw- 

threads,  table  of,  454. 

“ “ system  of  screw  threads,  452. 

Units  of  heat,  68,  69. 

Unwin,  W.  C.,  202. 

Utica  Steam  Gauge  Co.,  243. 


Vacuum,  53,54,534. 

“ brake,  application  of,  536. 

“ “ Eames'  534-539. 

“ “ release  of.  538. 

“ in  smoke-box,  172. 

“ lever,  526. 

“ line,  53,  56,  60,  62,  63. 

Valve,  43,  46,  51. 

“ ‘ arrangement  of,  50. 

“ broken,  660. 

“ changes  in  motion  of,  341. 

“ check,  218. 

“ conductor’s,  502,  524,  528,  529. 

“ engineer’s  brake,  484, 485,  487,  488,  489, 
490,  491,  492,  493,  495,  496,  504,  509,  510, 
521 , 524,  526. 

“ engravings  of,  50. 

“ face,  93,  97,  282. 

“ “ broken, 661. 

“ faces,  wear  of,  609. 

“ gear,  281-356. 

“ “ arrangement  of,  49. 

“ “ car.e  of,  608,  609. 

“ “ defects  of,  77. 

“ “ imperfection  of,  62. 

“ “ model  of,  341. 

“ “ testing  of,  341. 

“ graduating,  488,  509. 

“ leak  in,  337. 

“ middle  position  of,  282. 

“ motion,  diagram  of,  297,  298. 

“ “ of,  100. 

“ movement  of,  91,  340. 

“ pressure,  216. 

“ “ retaining,  506, 507, 533. 

“ quick  acting  triple,  504,  507,  508,  510, 
511,  512,  513,  523,  530. 

“ rod,  43. 

“ rotary,  493,  494,  495,  496,  497. 

“ seat,  41,263. 

“ slide,  41,  78,  91,281,356. 

“ “ action  of,  89. 

“ “ engravings  of,  79,  80. 

“ “ setting  of,  564,  355,  356. 

“ stem,  43,  1 17,  267. 

“ “ broken,  659,  660. 

“ “ change  of  length  of,  659. 

“ suction,  216. 

“ tank,  220,  470. 

“ tender,  463,  464. 


708 


Index. 


Val— Wat 

Valve,  throttle,  254. 

“ triple,  484,  485,  486,  487,  489,  493,  494, 
496,  497,  501,  504,  507,  523,  530. 

“ yoke,  broken,  660. 

Valves,  main,  leak  in,  605,  609. 

“ oiling  of,  626. 

“ 11  “ 268. 

“ proportions  of,  349. 

“ safety,  240. 

“ should  cut  off  alike  on  both  sides,  610. 
“ triple,  care  of,  532. 

Vapor,  26. 

Variable-exhausts,  260. 

Velocity,  increase  or  diminution  of,  3,  9. 

“ of  falling  bodies,  4,  5,  106. 

“ “ “ body,  calculation  of,  6. 

“ “ moving  body,  3. 

“ “ piston,  103. 

“ “ “ and  cross-head,  104. 

“ “ “ diagram  of,  105. 

“ “ surfaces,  effect  of  on  lubrication, 

442. 

“ “ trains,  resistance  at,  586,  587. 

, Venous  bleeding,  665. 

Vertical  boilers,  124,  126. 

“ disturbance  of  counterweights,  388. 
“ section  xv. 

Volume  of  air  or  steam,  30. 

“ “ steam,  68. 

“ “ “ and  water,  31. 

“ “ “ diagram  of,  52. 

“ “ “ relation  of  to  heat  and 

pressure,  56. 

Vomiting,  361. 

“Vortex”  blast-pipe,  260. 

V-thread,  452,  453. 


AVages  of  engineers  and  firemen,  595. 
Wagon,  393. 

“ of  locomotive,  392. 

“ top,  211. 

Waist  of  boiler,  117,  168. 

Warm  water  test,  599,  600. 

Washer,  460. 

Washing  boilers,  601. 

“ out  boiler,  602,  634. 

Waste,  cost  of,  595. 

“ cotton  or  woolen,  465. 

“ of  air,  526. 

“ supply  of,  618. 

“ use  of,  610. 

Watchmen,  cost  of,  595. 

Water,  amount  evaporated,  547. 

“ analysis  of,  472. 

“ and  steam,  pressure  and  temperature 

of,  28. 

“ “ “ volume  of,  31. 

“ circulation  of,  181. 

“ composition  of,  551. 

“ corrosive,  601. 

“ crane,  470,  471. 

“ danger  of  too  little  or  none,  617. 

“ evaporated,  546 

“ evaporation  of,  26. 

“ exhaust  of  supply  of,  662. 


Wat— Wei 

Water,  expansion  of  by  heat,  617. 

“ freezing  of  in  locomotive,  635. 

“ gauge,  236-238. 

“ “ breaking  of,  239. 

“ “ care  of,  604. 

“ grates,  252,  580,  581. 

“ heating  of,  26. 

“ height  of,  in  boiler,  621,  648. 

“ impure,  470. 

“ in  boiler,  617. 

“ “ “ height  of,  604. 

“ “ “ how  affected  by  grades,  625. 

“ “ cylinder,  621. 

“ “ pumps,  freezing  of,  628 

“ low,  239. 

“ muddy,  use  of,  622. 

“ of  ammonia,  472,  473. 

“ pure,  need  of,  602. 

“ purity  of,  26. 

“ quality  of,  472. 

“ quantity  carried  in  boilers,  211. 

“ evaporated  by  pound  of  coal, 
172. 

“ regulation  of  supply,  220. 

“•  scoop,  462,  463. 

“ source  of  supply  of,  472. 

“ space,  171. 

“ stations,  461 , 469. 

“ stored  up  in  boiler,  547. 

“ supplied  to  boiler,  216. 

“ supply,  how  regulated,  620. 

“ “ of,  461,469. 

“ “ “ in  ascending  grades,  625. 

“ table,  Buchanan’s,  576-578. 

“ “ cleaning  of,  617. 

“ tank,  118,  461. 

“ “ care  of,  615. 

“ tanks  and  turn-tables,  469-481. 

“ temperature  of,  26. 

“ trough,  462. 

“ tubes,  580,  581.  • 

“ variation  of  level,  239. 

Weakness  of  boiler,  599. 

Weather,  effects  of  change  of,  637. 

Wedges,  416. 

“ care  of,  611. 

Weight,  adhesive,  544,  545. 

“ balance,  377. 

“ distribution  of,  425,  426,  427, 

“ of  cars,  515,  517. 

“ “ locomotive,  size  of  boiler  limited 

by,  549. 

“ “ revolving  and  reciprocating  parts, 

385. 

“ “ steam,  diagram  of, .52. 

“ “ train,  540. 

“ on  driving  wheels,  370. 

“ “ foot- board,  effect  of,  438. 

1 “ wheels,  distribution  of,  540. 

“ raised  by  pressure  of  air,  engraving 
of,  25. 

“ “ “ “ “ steam, diagram 

of,  29. 

“ represented  by  a line,  engraving  of, 
14. 

“ suspended,  381. 


Index. 


709 


Wei— Whe 


Whe — Zig 


Weights,  revolving,  379,  380. 

“ unbalanced,  effect  of,  376,  377. 

Wells,  as  sources  of  water  supply,  472. 

Welt,  200,  206. 

Welted  seam,  204. 

“ seams,  advantages  of,  206. 

Western  States,  601. 

Westinghouse  air-brake,  482-520.  Plate  VI. 

“ “ care  and  use  of,  521- 

532. 


“ “ Co.,  521. 

“ George,  Jr.,  482,  483,  507. 

Wet  steam,  211. 

“ “ effect  of,  624. 

Wheel-base,  406. 

“ length  of,  121. 
broken,  655,  657. 
centres,  113,  407. 

“ standard  sizes  of,  408. 
effect  of  revolving,  376. 
guards,  439. 

Wheels,  112. 

adhesion  of,  112,  540,  542. 
and  boiler,  relation  of  size  of,  549. 
back  or  trailing,  116. 
care  of,  610. 


coned,  diagram  of,  396,  397. 

“ “ action  of,  398,399. 

diagram  of  action  of,  393. 
diagrams  of  action  on  curve,  394. 
driving,  action  of,  357-669. 

“ adhesion  of,  friction  of,  load 

on,  weight  on,  370. 

“ construction  of,  406. 

“ engraving,  406. 

“ number  needed,  116. 

effect  of  size  of,  549. 
force  required  to  turn  them,  541. 
friction  of,  112. 
limit  to  size  of,  550. 
paper,  410. 
plan  of,  402,  403. 
position  of,  121. 
revolution  of,  112. 
size  of,  541,  543. 
sliding  of,  395,  397. 
slipping  of,  124. 
slip  of,  112,  370,  541,  619. 

“spread”  of,  406. 
steel  tired,  410. 
truck,  116. 

“ construction  of,  409. 

“ engraving  of,  410. 
use  of,  392. 


Wheels,  weight  on,  543. 

“ wrought  iron,  410. 

Whiskey,  how  and  when  to  give  it,  668,  671. 

Whistle,  247,  248. 

“ blowing  of,  619. 

“ valve,  care  of,  604. 

“Wild”  engine,  629. 

Williams,  C.  Wye,  553. 

“ White  & Co.,  473. 

“ Wye,  564. 

Wilson  on  boiler  construction,  599. 

“ “ steam  boilers,  621. 

“ Robert,  553. 

Wilson’s  treatise  on  boilers,  190,  195. 

“ “ “ steam  boilers,  209. 

Wind,  12. 

Windlass,  515. 

“ brake,  482. 

Windows,  show,  559. 

Wire  drawing,  steam,  620. 

“ drawn,  steam,  318. 

“ netting,  212. 

“ “ clogged,  602. 

“ “ destruction  of,  602. 

“ “ dimensions  of,  215. 

“ “ effect  of,  582,  583, 

“Wobble,”  376. 

Wood,  burning  chimney,  engraving  of,  214. 

“ conducting  and  radiating  power  of,  33. 
“ grate  bars  for,  252. 

“ lagging,  burning  of,  605. 

Wool,  conducting  power  of,  33. 

Woolen  waste,  465. 

“ “ use  of,  610. 

Work,  calculation  of,  34. 

“ done  by  given  weight  of  steam,  65. 

“ “ “ ru  lb.  of  steam,  68. 

“ “ per  unit  of  heat,  67. 

“ energy  and  the  mechanical  equivalent 
of  heat,  34. 

“ excessive  amount  of,  638. 

“ performance  of,  62. 

Working  pressure,  28,  55. 

“ steam  expansively,  369. 

“ water,  268,  602. 

Wrecking-car,  647. 

Wrist-pin,  275. 

Wrought-iron,  strength  of,  188. 

“ wheels,  410. 


Y,  480,  481. 


Zig-zag  rivets,  200. 


PLATE  I. 


STATIONARY  ENGINE. 


ULfdj  | Hj  | |._L|1X1 


PASSENGER  LOCOMOTIVE,  BUILT  BY  THE  BALDWIN  LOCOMOTIVE  WORKS,  PHILADELPHIA. 


PLATE  IV. 


library 

OF  THE 

DIVERSITY  ofILLIN! 


PLATE  V 


PLAN  OF  PASSENGER  LOCOMOTIVE,  BUILT  BY  THE  BALDWIN  LOCOMOTIVE  WORKS,  PHILADELPHIA. 


PLATE  VI 


Air  Gauge 


Pump  Lubricator 


:incer’s^j 
e- Valve  ( 
J Pipe  to 
jservoir 


i I Air  Pump 


r c to  cut 
de  Valve 
I re  than 
' ;ine  is 


Engineer’s 

Brake-Valve 

Reservoir 


Train 


PLATE  VI. 


LIBRARY 

Of  THE 

UNIVERSITY  of  ILLINOIS 


